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3cf74a52-f324-41a8-a101-8e62429fba5b
| 3 |
3. The rate of formate dissociation from cytochrome a2+ a33+ -HCOOH is faster than its rate of dissociation from a3+ a33+ -HCOOH, especially in the presence of cytochrome c. The Ki for formate inhibition of respiration is a function of the reduction state of the system, varying from 30 mM (100% reduction) to 1 mM (100% oxidation) at pH 7.4
|
3cf74a52-f324-41a8-a101-8e62429fba5b
| 4 |
, 30 degrees C. 4. Succinate-cytochrome c reductase activity is also inhibited by formate, in a reaction competitive with succinate and dependent on [formate]2. 5. Formate inhibition of ascorbate plus N, N, N', N'-tetramethyl-p-phenylenediamine oxidation by intact rat liver mitochondria is partially released by uncoupler addition.
|
3cf74a52-f324-41a8-a101-8e62429fba5b
| 5 |
Formate is permeable through the inner mitochondrial membrane and no differences in 'on' or 'off' inhibition rates were observed when intact mitochondria were compared with submitochondrial particles. 6. NADH-cytochrome c reductase activity is unaffected by formate in submitochondrial particles, but mitochondrial oxidation of glutamate plus malate is subject both to terminal inhibition at the cytochrome aa3 level and to a slow extra inhibition by formate following uncoupler addition, indicating a third site of formate action in the intact mitochondrion.
|
b75dffca-7f70-4746-a202-16cea08616f1
| 0 |
The coupling factor of photophosphorylation and the electric properties of the thylakoid membrane. The rate of ATP synthesis of illuminated chloroplasts is correlated with the electric conductance of their inner membranes. In agreement with previous studies it is shown that ATP synthesis is paralleled by an increased conductance of the thylakoid membrane.
|
b75dffca-7f70-4746-a202-16cea08616f1
| 1 |
This conductance together with the ability to form ATP is abolished if chloroplasts are treated with an antibody against the coupling factor CF1. It is not influenced by the fragmented monovalent antibody. This parallels the lack of influence of the fragmented antibody on ATP synthesis in contrast to its influence on hydrolysis and exchange reactions.
|
b75dffca-7f70-4746-a202-16cea08616f1
| 2 |
We conclude that there are different sites for the interaction of the coupling factor with adenine nucleotides. Extraction of the coupling factor is shown to increase the membrane conductance by more than two orders of magnitude. Reincorporation of the crude coupling factor partially restores the net conductance of the membrane (increase in resistance by a factor of 2.5
|
b75dffca-7f70-4746-a202-16cea08616f1
| 3 |
), while a higher degree of restoration was observed for ATP synthesis and the proton conductivity of the membrane. We conclude that the extraction procedure opens different conductive channels in the membrane; a proton specific one, possibly associated with the binding protein for the coupling factor, plus other channels for "non-protons" which in contrast to the proton channel cannot be plugged by reincorporation of the coupling factor.
|
5fe4e02a-90da-4902-a909-02220c6ceb7c
| 0 |
Evidence against proton gradient formation being the cause of chlorophyll fluorescence quenching by N-methylphenazonium methosulfate. In strong illumination, 3-(3, 4-dichlorophenyl)-1,1-dimethylurea (DCMU)-poisoned chloroplasts exhibit a high yield of chlorophyll fluorescence while P-700 turnover, proton uptake, and phosphorylation are inhibited and a pH gradient is undectectable.
|
5fe4e02a-90da-4902-a909-02220c6ceb7c
| 1 |
When 10muM N-methylphenazonium methosulfate (PMS) is included, the fluorescence yield in light is substantially reduced, and when 100 muM ascorbate is also included, the yield is diminished approximately to the level in darkness. Only very slight increases in P-700 turnover and proton uptake (but no detectable pH gradient) accompany the fluorescence yield decline.
|
5fe4e02a-90da-4902-a909-02220c6ceb7c
| 2 |
When 10muM PMS and 15 mM ascorbate are added to poisoned chloroplasts (the oxygen concentration being greatly reduced), P-700 turnover, proton uptake, the pH gradient and phosphorylation all reach high levels. In this case, the yield of chlorophyll fluorescence is low and is the same in both light and dark.
|
5fe4e02a-90da-4902-a909-02220c6ceb7c
| 3 |
Further addition of an uncoupler eliminates proton uptake, the pH gradient and phosphorylation but does not significantly elevate the fluorescence yield. From these observations we suggest that, in DCMU-poisoned chloroplasts, the fluorescence quenching with PMS occurrs by a mechanism unrelated to the generation of a phosphyorylation potential.
|
5fe4e02a-90da-4902-a909-02220c6ceb7c
| 4 |
With chloroplasts unpoisoned by DCMU, PMS quenches fluorescence and considerably stimulates proton uptake, the pH gradient and phosphorylation. However, in this case, PMS serves to restore net electron transport.
|
224660eb-bc8f-4b40-8877-7b10f388dda3
| 0 |
The accumulation of superoxide radical during the aerobic action of xanthine oxidase. A requiem for H2O4. The action of xanthine oxidase upon acetaldehyde or xanthine at pH 10.2 has been shown to be accompanied by substantial accumulation of O2- during the first few minutes of the reaction. H2O2 decreases this accumulation of O2- presumably because of the Haber-Weiss reaction (H2O2+O2- leads to OH- +OH+O2) and very small amounts of superoxide dismutase eliminate it.
|
224660eb-bc8f-4b40-8877-7b10f388dda3
| 1 |
This accumulation of O2- was demonstrated in terms of a burst of reduction of cytochrome c, seen when the latter compound was added after aerobic preincubation of xanthine oxidase with its substrate. The kinetic peculiarities of the luminescence seen in the presence of luminol, which previously led to the proposal of H2O4-, can now be satisfactorily explained entirely on the basis of known radical intermediates.
|
73a4d18c-ef02-4706-85e3-7425df953ac4
| 0 |
The 520 nm absorbance changes in Scenedesmus obliquus and its relation to photosystem I. The kinetics (region of seconds) of the light-induced 520 nm absorbance changes and its dark reversal have been studied in detail in the wild type and in some pigment and photosynthetic mutants of Scenedesmus obliquus.
|
73a4d18c-ef02-4706-85e3-7425df953ac4
| 1 |
The following 5 lines of evidence led us to conclude that the signal is entirely due to the photosystem I reaction modified by electron flow from Photosystem II. Gradual blocking of the electron transport with 3(3,4-dichlorophenyl)-1,1-dimethylurea resulted in diminution and ultimate elimination of the biphasic nature of the signal without reducing the extent of the absorbance change or of the dark kinetics.
|
73a4d18c-ef02-4706-85e3-7425df953ac4
| 2 |
On the contrary, blocking electron flow at the oxidizing side of plastoquinone with 2,5-dibromo-3-methyl-6-isoprophyl-p-benzoquinone or inactivating the plastocyanin with KCN, prolonged the dark reversal of the absorbance change apart from abolishing the biphasic nature of the signal. Action spectra clearly indicate that the main signal (I) is due to electron flow in Photosystem I and that its modification (Signal II) is due to the action of Photosystem II.
|
73a4d18c-ef02-4706-85e3-7425df953ac4
| 3 |
Signal I is pH independent, whereas Signal II demonstrates a strong pH dependence, parallel to the O2-evolving capacity of the cells. Chloroplast particles isolated from the wild type Scenedesmus cells demonstrated in the absence of any added artificial electron donor or acceptor and also under non-phosphorylation conditions the 520 nm absorbance change with approximately the same magnitude as whole cells.
|
73a4d18c-ef02-4706-85e3-7425df953ac4
| 4 |
The dark kinetics of the particles were comparatively slower. Removal of plastocyanin and other electron carriers by washing with Triton X-100 slowed down the kinetics of the dark reversal reaction to a greater extent. A similar positive absorbance change at 520 nm and slow dark reversal was also observed in the Photosystem I particles prepared by the Triton method.
|
73a4d18c-ef02-4706-85e3-7425df953ac4
| 5 |
Mutant C-6E, which contains neither carotenoids nor chlorophyll b and lacks Photosystem II activity, demonstrates a normal signal I of the 520 nm absorbance change. This latter result contradicts the postulate that carotenoids are the possible cause of the 520 nm absorbance change.
|
03c77535-64ac-460c-96a7-f8ac1c41340d
| 0 |
Pyruvate flux into resealed ghosts from human erythrocytes. The kinetics of pyruvate transport across the isolated red blood cell membrane were studied by a simple and precise spectrophotometric method: following the oxidation of NADH via lactate dehydrogenase trapped within resealed ghosts. The initial rate of pyruvate entry was linear.
|
03c77535-64ac-460c-96a7-f8ac1c41340d
| 1 |
Influx was limited by saturation at high pyruvate concentration. Pyruvate influx was greatly stimulated by increasing ionic strength in the outer but not the inner aqueous compartment. The Km ranged from 15.0 mM at mu = 0.05 to 3.7 mM at mu = 0.01, while the V went from 0.611
|
03c77535-64ac-460c-96a7-f8ac1c41340d
| 2 |
- 10(15) to 0.137 - 10(-15) mol - min-1 - ghost-1. Ionic strength was shown to affect the translocation step and not pyruvate binding. The energy of activation of pyruvate flux into resealed ghosts was 25 kcal/mol, similar to that found in intact red blood cells.
|
03c77535-64ac-460c-96a7-f8ac1c41340d
| 3 |
Inhibitors of pyruvate influx included such anions as thiocyanate, chloride, bicarbonate, alpha-cyanocinnamate, salicylate and ketomalonate (but not acetate); noncompetitive inhibitors were phloretin, 1-fluoro-2,4-dinitrobenzene, 4-acetamido-4'-isothiocyanate-stilbene-2,2'-disulfonic acid and o-phenanthroline/CuSO4 mixtures. The last reagent, known to induce disulfide links in certain membrane proteins, blocked the ionic strength stimulation of pyruvate influx in this study.
|
897aa94b-caad-4765-918f-3ad870f40951
| 0 |
Heme models. I. Solution behavior of a water soluble iron porphyrin. A well-behaved water soluble iron-porphyrin system, meso-tetra-(4-carboxyphenyl) porphinato iron (III) was synthesized. Its solution behavior is described using visable and electron paramagnetic resonance (EPR) spectroscopy. The complex exists in solution as three distinct forms of bridged dimers, oxo, hydroxo and aquo, with the following pK's:
|
897aa94b-caad-4765-918f-3ad870f40951
| 1 |
oxo + H+ in equilibrium hydroxo, pK = 9.58; hydroxo + H+ in equilibrium aquo, pK = 6.72. In the presence of excess imidazole the second pK is found to be 7.05. Detailed analysis of the interaction of the hydroxo-bridged form with imidazole is presented.
|
897aa94b-caad-4765-918f-3ad870f40951
| 2 |
It is found that one dimer unit simultaneously binds two imidazole molecules, with an over-all equilibrium constant log Keq = -1.22. EPR spectra are presented for the various forms of iron-porphyrin discussed.
|
e3dc0616-af78-423b-88af-70334d79e85e
| 0 |
17 beta-Hydroxysteroid dehydrogenase of the sheep ovary : purification, properties and substrate binding site. Sheep ovarian 17 beta HSDH has been purified about 1000 fold to a specific activity of 0.5 IU/mg protein, using DEAE cellulose chromatography, affinity chromatography on estrone-amino caproate-Sepharose and a second DEAE cellulose chromatography.
|
e3dc0616-af78-423b-88af-70334d79e85e
| 1 |
The molecular weight is 70,000 ; the pH optimum for activity is 9.2 and the energy of activation is 16.5 Kcal/mole. The kinetics of the oxidation of estradiol and many analogues have been studied at various concentrations and in the presence of different amounts of coenzyme. The data are in agreement with a compulsory order mechanism with the binding of NAD+ as the first substrate.
|
e3dc0616-af78-423b-88af-70334d79e85e
| 2 |
Sheep ovarian 17 beta HSDH accepts subtituents in position C3, C11, C13 ; the substrate binding site is open in this region. On the contrary, the binding requirements are strict for the region of C10 since the presence of a C19 methyl group impairs binding and (or) oxidation of the steroid.
|
e3dc0616-af78-423b-88af-70334d79e85e
| 3 |
Sheep ovarian and human placental 17 beta HSDH have close analogies : molecular weight, pH optimum, substrate binding site requirements. Their reaction mechanisms are different : random for the placental 17 beta HSDH, compulsory order for the ovarian 17 beta HSDH : this can be explained by the effect of the coenzyme upon the binding of the substrate :
|
e3dc0616-af78-423b-88af-70334d79e85e
| 4 |
without effect on placental enzyme, the coenzyme fixation enhances the affinity of the ovarian 17 beta HSDH for any substrate.
|
89fd35aa-f74e-4444-9d95-ed9459b16cdf
| 0 |
Complete purification and studies on the structural and kinetic properties of two forms of yeast valyl-tRNA synthetase. Two forms of baker's yease valyl-tRNA synthetase have been purified to apparent homogeneity by classical methods. It was demonstrated that one of the two forms of the enzyme originates from the other by proteolysis, the respective amounts of each form depending on the physiological state of the yeast.
|
89fd35aa-f74e-4444-9d95-ed9459b16cdf
| 1 |
The species mainly isolated from exponential growing yeast cells is a monomer of 130,000 daltons molecular weight. In stationary phase cells or in commercial yeast the major species is a degraded monomer of 120,000 daltons molecular weight ; however when the purification is carried out in the presence of phenylmethyl-sulphonyl fluoride, or diisopropylfluorophosphate large amounts of the not - degreded monomer can be obtained.
|
89fd35aa-f74e-4444-9d95-ed9459b16cdf
| 2 |
Of great practical usefulness is the fact that large amounts of the native enzyme can be obtained pure after only two chromatographic steps on DEAE-cellulose and hydroxylapatite. The kinetic constants for valine, ATP and tRNAVal were determined, as well as the optimum aminoacylation conditions. It was found that the specific activity of the nondegraded valyl-tRNA synthetase is higher than that of the proteolysed enzyme for the aminoacylation reaction.
|
89fd35aa-f74e-4444-9d95-ed9459b16cdf
| 3 |
On the contrary, both forms have the same ATP-pyroposphate exchange activity. The amino acids composition of the native enzyme was established. The tryptic fingerprints of the two valyl-tRNA synthetases were studied. Essentially similar maps were obtained. The number of the spots in the fingerprints indicates that the enzymes contain a high proportion of repeated sequences.
|
16f1cb0c-2860-4839-ad94-0da5945a2684
| 0 |
[Rat liver plasma membrane phospholipase A]. The plasma membranes phospholipase A2 studied in situ shows very little sensitivity for pH variations ; the optimal concentration for Ca++ is 5 mM ; the enzymatic kinetics are of the Michaelis type. An inactive state of the phospholipase A2 exists :
|
16f1cb0c-2860-4839-ad94-0da5945a2684
| 1 |
when rats are injected with heparin, their plasma membranes contain a very low phospholipase A2 activity. These membranes recover a high A2 activity if they are incubated in the presence of a rat platelets lysate. Treatment of membranes by NaCl 1 M displaces phospholipase A1 and phospholipase A2 but for the latter only when being in active state.
|
16f1cb0c-2860-4839-ad94-0da5945a2684
| 2 |
Treatment of animals, conditions of preparation and of incubation of membranes influence the respective amounts of phospholipases A1 and A2 present in these membranes and are discussed in this paper. The localisation of these enzymatic proteins inside the membrane according to the membranous model proposed by Singer et al.
|
16f1cb0c-2860-4839-ad94-0da5945a2684
| 3 |
[18] is also discussed.
|
8050a01c-d6a9-4c49-8dcb-4be232baf2dd
| 0 |
Phosphate uptake in Chlorella pyrenoidosa : II. Effect of pH and of SH reagents. The sensitivity of the phosphate transport system to pCMPS after phosphate starvation is dependent on protein synthesis. This fact is related to the development of transport activity at alkaline pH. In non-starved cells, the presence of only one peak of maximal activity for phosphate uptake at neutral pH (at low and high concentration) has been observed.
|
8050a01c-d6a9-4c49-8dcb-4be232baf2dd
| 1 |
However, in phosphate starved cells, two peaks of maximal activity (at low phosphate concentration) at neutral and alkaline pH are present. In starved cells, pCMPS inhibits more intensely the phosphate transport activity at alkaline pH than at neutral pH. By contrast, NEM inhibits the phosphate transport more strongly at neutral than at alkaline pH.
|
8050a01c-d6a9-4c49-8dcb-4be232baf2dd
| 2 |
Phosphate uptake at neutral and alkaline pH are sensitive to osmotic shock, but phosphate uptake at alkaline pH is decreased more than at neutral pH. The results could be interpreted either by assuming that the membrane surroundings change during phosphate starvation or that two transport systems are present in starved cells whereas only one transport system exists in non-starved cells.
|
429a5b91-8a5c-45d2-8cda-89fdeb55b093
| 0 |
Possible occurrence for histidyl and cysteyl residues in the catalytic center of rat liver mitochondrial D (-)-beta-hydroxybutyrate dehydrogenase. 1. Rat liver mitochondrial D(-)-beta-hydroxybutyrate dehydrogenase (submitochondrial particles and partially purified preparation) is inhibited by some dicarboxylates, especially by malonate and succinate. The inhibition is reversible and competitive with beta-hydroxybutyrate while uncompetitive with acetoacetate, NAD and NADH:
|
429a5b91-8a5c-45d2-8cda-89fdeb55b093
| 1 |
the inhibition is maximal at pH 6 and decrease with increasing pH. 2. Diethylpyrocarbonate (which reacts preferentially with histidyl residues at pH 6.6) inactivates the dehydrogenase at pH 6.1, beta-hydroxybutyrate protects against inactivation, this inactivation being almost completely released by hydroxylamine. The diethylpyrocarbonate-treated enzyme shows an absorbance increase at 242 nm which is characterisitic of reaction between diethylpyrocarbonate and histidyl residue.
|
429a5b91-8a5c-45d2-8cda-89fdeb55b093
| 2 |
3. The optimum pH of the enzyme for beta-hydroxybutyrate oxidation is around 8.2, while for acetoacetate reduction, the optimum pH is around 7. 4. All these results favour the existence of a histidyl residue in the catalytic center and taking into account previous results concerning the effect of thiol reagents on the same enzyme and especially, the protective effect of NAD+ and NADH against these reagents [11] we discuss the possible occurrence of, at least, one histidyl and one cysteyl residue on the catalytic center.
|
21948e03-f343-4a38-9897-844399e9da08
| 0 |
[Mechanism of glutaraldehyde-protein bond formation]. Commercial aqueous 25% glutaraldehyde solutions contain no stable derivative of this aldehyde, but compounds of variable molecular weight which easily revert to glutaraldehyde. The effect of pH on the reaction of glutarldehyde with amino acids and on the stability of the products under acid conditions, shows the importance of the structure modification of the dialdehyde which occurs when pH increases, and even leads to precipitation in highly alkaline solutions.
|
21948e03-f343-4a38-9897-844399e9da08
| 1 |
This precipitate results from aldol condensation of glutaraldehyde molecules. It contains aldehyd groups conjugated with ethylenic double bonds. Such a structure reacts with amino groups to give an imino bond, stabilized by resonance with the ethylenic bond, and does not undergo Michael-type addition reactions. Therefore, glutaraldehyde does not react with proteins under its free form, but as an unsaturated polymer, which gives imino bonds stabilized by conjugation.
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31a031f2-af79-4d7e-b1bd-e232d1d25a48
| 0 |
Purification and properties of cyclic AMP dependent and independent protein kinases from rat pancreas. Three protein kinases Ko, K1, and KII have been extracted from rat pancreas homogenate, Ko is not stimulated by cyclic AMP. K1 is poorly stimulated by cyclic AMP (1.3 times), Ku is highly stimulated (6 times). The specificity of KII with respect to various nucleotides and cyclic nucleotides has been determined. K1 and KII account for the total cyclic AMP dependent protein kinase activity in the homogenate.
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c2929ede-07c6-4f79-8da2-16154b69ff6e
| 0 |
[Decanoic acid, new precursor for in vitro biosynthesis of oleic acid by a plant subcellular fraction]. Various membraneous fractions prepared from a cauliflower homogenate synthesize radioactive oleic acid when they are incubated in a 14C-decanolate solution. The more active fraction is formed of vesicles sedimenting at 30,000 g x 20 mn (heavy microsomes).
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c2929ede-07c6-4f79-8da2-16154b69ff6e
| 1 |
The labelled precursor is transformed by this fraction mainly into oleic acid and hydroxyacids. ATP, NADPH, CoA and oxygen are required for these reactions. Labelled fatty acids, longer than lauric and (i.e. 14C-myristic, 14C-palmitic and 14C-stearic acids) are not transformed into oleic acid by the subcellular fraction studied in this paper.
|
8222fc20-7af3-4d50-8a31-4c959a51b588
| 0 |
[Acetylcholinesterase. II. Experimental aspects of interaction with reversible effectors under conditions of high ionic strength]. Interaction of usual effectors with acetylcholinesterase (EC 3.1.1.7) from bovine erythrocytes was examined under conditions of high ionic strength (gamma/2 greater than or equal to 0,1). Detailed kinetic investigation of the hydrolysis of acetylcholine by acetylcholinesterase in the presence of modifiers shows that the effects produced by numerous quaternary nitrogen compounds on the enzyme can be explained on the basis of binding of the effectors to the anionic subsite of the active center.
|
8222fc20-7af3-4d50-8a31-4c959a51b588
| 1 |
The various kinetic behaviors, that are observed, are dependent on the relative values of the deacetylation rate constant ak of the complex acetylated enzyme-modifier and of the rate constant k-2 defined by : (see article) with respect to the value of the deacetylation rate constant K of the acetylated enzyme.
|
8222fc20-7af3-4d50-8a31-4c959a51b588
| 2 |
If a identical to [1--(k/k-2)]-1, it is shown that interaction of the enzyme with tetraethylammonium, pentamethonium, hexamethonium and gallamine ions is characterized by : a greater than a and k-2 greater than k therefore, these modifiers accelerate deacetylation. On the other hand, inhibition of acetylcholinestase by methylpyridinium, d-tubocurarine, tetra-n-propylammonium, tetra-n-butylammonium, decamethonium and succinylbischoline is consistent with one of the conditions :
|
8222fc20-7af3-4d50-8a31-4c959a51b588
| 3 |
a less than a and k-2 greater than or equal to k or a greater than a and k-2 less than k and inhibition by tetramethylammonium, phenyltrimethylammonium, 3-hydroxyphenyl-triethylammonium, N-methylacridinium and bis (3-aminopyridinium)-1,10-decane ions agrees with one of the two previous conditions or with :
|
8222fc20-7af3-4d50-8a31-4c959a51b588
| 4 |
(see article) consequently, the effect of these ligands on the deacetylation step is undetermined. However, the effects of choline chloride, thiazinamium methyl sulfate and thioridazine hydrochloride are not entirely consistent with this mechanism but support the existence of a functional peripheral anionic site which is distinct from the anionic subsite of the active center.
|
ed046a02-8bdb-43fc-964e-6f8815bff89c
| 0 |
[Interactions of phosphorylethanolamine analogs with phosphorylethanolamine-citidylyltransferase]. Kinetic studies of ethanolaminephosphate-cytidylyltransferase (E.C. 2.7.7.14) from rat liver have been carried out in presence of structural analogues of ethanolaminephosphate : these compounds acted as inhibitors of the enzyme: - 2-aminoethylphosphonate behaved as a substrate and a competitive inhibitor to phosphorylethanolamine:
|
ed046a02-8bdb-43fc-964e-6f8815bff89c
| 1 |
the Km value of 2-aminoethylphosphonate was nearly the same as its Ki value, at pH = 5,5 (30 X 10(-3) M and 24 x 10(-3) M, respectively). - 3-aminopropylphosphonate was also a competitive inhibitor. It appeared to be the best inhibitor at pH optimum (pH = 7,7).
|
ed046a02-8bdb-43fc-964e-6f8815bff89c
| 2 |
- 1-aminoethylphosphonate behaved as a noncompetitive inhibitor. However, cytidylyltransferase was relatively specific, inhibitions being always weak. Inhibitory power of phosphonates was stimulated by Mg++.
|
47de6b11-4d2a-4bd6-80c0-9c256f894c79
| 0 |
[Purification and properties of aromatic L-amino acid decarboxylase (4.1.1.28) of rat brain]. L-aromatic aminoacid decarboxylase has been purified more than thousand times from homogenates of rat brain, in several steps : centrifugation, DEAE-cellulose, CM cellulose, hydroxylapatite, DEAE sephadex. Its properties have been studied, most of them on an intermediate fraction of the purification, because of the instability of the purified enzyme in spite of the addition of different stabilizing agents :
|
47de6b11-4d2a-4bd6-80c0-9c256f894c79
| 1 |
the enzyme decarboxylates 5-hydroxytryptophan (5 HTP) and DOPA in a ratio constant throughout the purification but does not decarboxylate tryptophan, tyrosine, histidine at a measurable rate. Optimum pH, Km, Vm, have been measured with 5 HTP and DOPA as substrates. The enzyme has a molecular weight of 115.000
|
47de6b11-4d2a-4bd6-80c0-9c256f894c79
| 2 |
, an apparent isoelectric point of 6,4-6,5. It is inhibited by serotonin, dopamine, some cations : Cu++, Fe++, Ni++ by N-ethylmaleimide, sodium dodecylsulfate. Some pyridoxal-5 phosphate (PLP) remains strongly bound to the enzyme. For relatively weak concentrations of substrate, the enzyme is inhibited by an excess of PLP ;
|
47de6b11-4d2a-4bd6-80c0-9c256f894c79
| 3 |
for weak concentrations of PLP, the enzyme in inhibited by an excess of substrate, particularly of DOPA. We also observe a spontaneous decarboxylation of the substrates that reaches a plateau and is enhanced by high concentrations of PLP, by serotonin, dopamine, Cu++ and reduced by mercaptoethanol and the presence of crude or boiled homogenates.
|
47de6b11-4d2a-4bd6-80c0-9c256f894c79
| 4 |
Several possible explanations of the spontaneous decarboxylation and of the enzymic inhibitions by an excess of PLP and by the substrates are given.
|
42c76fb0-d6e0-4ef0-be4d-bf48c9aec66b
| 0 |
[Characterization of some hydrolase activities in digestive juice of Achatina balteata]. The digestive juice of Achatina balteata, a giant snail of the West African Coast catalyses the hydrolysis of several natural and synthetic compounds. Enzymatic activities on lactose, o- and p-nitrophenyl-beta-D-galactoside, p-nitrophenyl-beta-D-glucoside, p-nitrophenyl-beta-D (and alpha-L-) fucoside, o-nitrophenyl-beta-D-xyloside, p-nitrophenyl-N-acetyl-beta-D-glucosaminide and phenolphthalein-glucuronide have been shown to be present.
|
42c76fb0-d6e0-4ef0-be4d-bf48c9aec66b
| 1 |
The effect of pH and substrate concentration on these activities were studied. The galactosidase, glucosidase and fucosidase activities were studied with respect to temperature, heat inactivation, pH stability and incubation with trypsin. Kinetic experiments suggest the presence of several galactosidase activities. This hypothesis is confirmed by specific staining after polyacrylamide gel electrophoresis.
|
42c76fb0-d6e0-4ef0-be4d-bf48c9aec66b
| 2 |
These activities showed a broad specificity towards galactosides and glucosides. The digestive juice showed no action on acetyl-L-tyrosine and benzoyl-L-arginine ethyl esters. However a small protease activity was observed on hemoglobine. No lipase activity was found. Sulfatase content was low compared to that of Helix pomatia.
|
3b10f5ac-8875-4bf1-b094-b6b5f12896fa
| 0 |
Characterization of the mannosyl and fucosyl transferases in the ovine anterior pituitary glands. Ovine anterior pituitary glands contain mannosyl- and fucosyl-transferases localized in the microsomes and able to incorporate mannose or fucose as such from GDP-mannose or GDP-fucose into endogenous glycoproteins. The requirements and conditions necessary for maximum activity were investigated. The value of the Km is very similar for the two enzyme systems, 3 X 10(-7) M in the case of mannosyl-transferases and 5 X 10(-7) M in the case of fucosyl-transferases.
|
70f4a9d0-460f-46bf-a41a-2c5b80057fab
| 0 |
Adjuvant and immunostimulating activities of water-soluble substances extracted from Mycobacterium tuberculosis (var. hominis). Water-soluble substances have been extracted from two strains of Mycobacterium tuberculosis var. hominis: the native hydrosoluble part (polysaccharide and peptidoglycan), a substance in which the polysaccharide moiety is less abundant than in the latter, the acetylated peptidoglycan and, finally a tetrasaccharide-heptapeptide.
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70f4a9d0-460f-46bf-a41a-2c5b80057fab
| 1 |
All four types of substances, when they were injected together with Freund's incomplete adjuvant, exerted an adjuvant effect on the production of delayed-type hypersensitivity to ovalbumin in the guinea pig and on the production of anti-influenza virus antibodies in the rabbit. Injected intravenously in the mouse, they increased the number of antibody-producing cells in the spleen and enhanced the graft versus host reaction;
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70f4a9d0-460f-46bf-a41a-2c5b80057fab
| 2 |
no effect was seen on the phagocytic activity of the reticulo-endothelial system. By contrast with wax D, the water-soluble substances were devoid of arthritis-inducing activity in the rat. Altogether, these water-soluble substances seem to be endowed with at least some of the adjuvant activities of Freund's complete adjuvant and some of the immunostimulant activities of a live Mycobacterium like BCG.
|
302de65c-422b-4261-8920-3a1afefde1b8
| 0 |
Arylsulfatases isoenzymes in metachromatic leucodystrophy/detection of a new variant by electrophoresis improvement of quantitative assay. Arylsulfatase A and B activities were assayed in leucocytes of 43 controls, 11 cases of Metachromatic Leucodystrophy and 7 parents or siblings of patients, using a new technique implying specific inhibitors for leucocyte enzymes. Heterozygotes can be determined, with a 50% value compared to the control, in variant B. Electrophoresis of leucocytes after enzymatic staining for arylsulfatase, is a complementary technique which allowed the detection of a new form of metachromatic leucodystrophy.
|
3a967f69-7ab4-4a3e-8593-752f6f2f04e5
| 0 |
Intrahepatic lymphoid tissue graft: course of the Gvh reaction induced by Peyer's patches. To investigate the thymus-dependent immune competence of Peyer's patches, the course of splenomegaly and hepatic perivascular infiltration (PVI) was studied as criteria of graft-versus-host reaction (GvhR). Parental or F1 hybrid lymphoid tissues, were intrahepatically implanted and the ability of Peyer's patches to induce a GvhR was compared to that of spleen, lymph nodes and thymus.
|
3a967f69-7ab4-4a3e-8593-752f6f2f04e5
| 1 |
A slight but significant delayed increase of spleen index was observed at the 40th post operative day following Peyer's patches implantation whereas the thymus did not induce any modification of this parameter. On the other hand, the PVI was a very early and precise criterion in monitoring the Gvh reaction induced by Peyer's patches, and allowed to postulate that at least one T-cell function is present within the Peyer's patches.
|
4e282a6c-8cf0-42e2-8296-413e4335e1f0
| 0 |
Marine sterols. III--The sterol compositions of oceanic jellyfish. The use of gas chromatographic mass spectrometric techniques to identify unresolved components. The sterol compositions of three oceanic jellyfish have been determined using gas chromatographic mass spectrometric techniques involving the use of two separate gas chromatographic column systems. The components in overlapping peaks have been identified by comparison of the mass spectra of peaks in the two column systems using subtractive techniques.
|
4e282a6c-8cf0-42e2-8296-413e4335e1f0
| 1 |
A mid-water animal, Periphylla periphylla, was found to contain a very complex and unusual sterol profile including rare 5alpha-stanols, whereas two other oceanic jellyfish Pelagia noctiluca and Atolla wyvillei contained similar mixtures of delta5 sterols to those previously isolated from coastal species.
|
003749b8-62d7-47ce-bd06-6d9d7ce645fc
| 0 |
The gas chromatographic mass spectrometric determination of trifluoroacetic acid in biological fluid. Application to halothane metabolism. The methyl ester of trifluoroacetic acid was prepared by reaction with N,N'-dimethylformamide dimethylacetal and was successfully passed through a gas chromatograph. Trifluoroacetic acid was detected by the use of gas chromatography and low and high resolution gas chromatography mass spectrometry in an acidic extract of an incubation medium containing microsomes, reduced nicotinamide adenine dinucleotide phosphate, oxygen and halothane.
|
003749b8-62d7-47ce-bd06-6d9d7ce645fc
| 1 |
However, trifluoroacetic acid could not be detected when nicotinamide adenine dinucleotide or oxygen was omitted from the incubation system. From these results, it was proved that halothane is oxidatively metabolized to trifluoroacetic acid by hepatic microsomes.
|
45b5f9b9-21c2-4c13-b46f-e9362afe2354
| 0 |
[Reciprocal influence of the graft vs. host reaction and pregnancy]. The graft versus host reaction (GVHR) was induced in mouse females-hybrids F1 (CBA X C57BL/6) by intravenous injection of suspension of the lymphoid cells of the spleen and of lymphoid nodes from C57BL/6 mouse females.
|
45b5f9b9-21c2-4c13-b46f-e9362afe2354
| 1 |
Pregnancy resulted from interbreeding of the test females with syngenic males 1--5 days before, and 1--10, 10--20, 30--40 and more than 40 days after the moment of the lymphoid cells injection, aggravated the GVHR induced transplantation disease. At the same time the GVHR under these conditions decreased the percentage of pregnant animals and brought to child-bearing disfunction of the test animals (stillbirth, death of pregnant females, miscarriage).
|
45b5f9b9-21c2-4c13-b46f-e9362afe2354
| 2 |
In some of the test mice aggravation of the GVHR was observed after delivery. Survival of the progeny decreased.
|
c910dbef-fdd0-479c-adba-39c23a300ff5
| 0 |
Studies on gamma-glutamyl transpeptidase in human and rabbit erythrocytes. Gamma-glutamyl transpeptidase transfers the gamma-glutamyl moiety of glutathione to a variety of acceptor amino acids. Through the operation of the gamma-glutamyl-cyclotransferase cycle, this enzyme has been implicated in the transport of amino acids into cells, especially the cells of the proximal tubules of kidney.
|
c910dbef-fdd0-479c-adba-39c23a300ff5
| 1 |
It has been reported to be present in rabbit erythrocytes. However, using white cell-free preparations, we have not been able to demonstrate the presence of gamma-glutamyl transpeptidase in human or rabbit erythrocytes either by measuring the utilization of GSH or by following the formation of the product.
|
c910dbef-fdd0-479c-adba-39c23a300ff5
| 2 |
14C-L-methionine was used as acceptor amino acid, and the formation of gamma-glutamyl-14C-L-methionine was followed. Using similar conditions, we have been able to demonstrate the presence of gamma-glutamyl transpeptidase in human and rabbit leukocytes and in human kidney. In contrast to a previous report, we were unable to find the accumulation of 5-oxoproline, an intermediate of the gamma-glutamyl-cyclotransferase pathway in human red cells incubated in Krebs-Ringer solution.
|
c910dbef-fdd0-479c-adba-39c23a300ff5
| 3 |
Immunologic studies demonstrated that human red cell membranes contained no protein antigenically similar to kidney gamma-glutamyl transpeptidase. Thus our studies indicated that in human and rabbit erythrocytes, the gamma-glutamyl transpeptidase-cyclotransferase pathway was not operative.
|
d379a821-b364-4e3c-997d-3c0b9f9de189
| 0 |
The pH dependence of quantitative ristocetin-induced platelet aggregation: theoretical and practical implications-a new device for maintenance of platelet-rich plasma pH. Quantitative ristocetin-induced platelet aggregation of normal platelet-rich plasma (PRP) decreased with time after PRP preparation. An increase in p H of the PRP with time proved to be responsible for this finding.
|
d379a821-b364-4e3c-997d-3c0b9f9de189
| 1 |
Diffusion of CO2from the plasma is the prime determinant of the change in pH. Since a complex combination of factors influences CO2 diffusion (surface area-to-volume relationship, capping, mixing, etc.) The change in pH is variable with time. Thus, quantitative ristocetin aggregation should be pH controlled.
|
d379a821-b364-4e3c-997d-3c0b9f9de189
| 2 |
A simple device for maintaining PRP pH constant by control of the ambient pCO2 was designed and found effective in keeping both pH and quantitative ristocetin aggregation constant over a prolonged period of time. It can be adapted for use in platelet aggregation studies employing other reagents. The pH dependence of ristocetin-induced platelet aggregation is consistent with other data supporting an elctrostatic interaction between the platelet, von Willebrand factor, and ristocetin.
|
d379a821-b364-4e3c-997d-3c0b9f9de189
| 3 |
We favor a model wherein ristocetin neutralizes some of the platelet's negative change and permits the von Willebrand factor to bridge sites on separate platelets to induce agglutination.
|
b7f6c8a2-5a5e-48cb-94b1-ea7fe8e6631b
| 0 |
[Case of congenital megaurethra associated with bilateral renal hyperplasia]. Authors report a very rare malformation of the external genital organs in a male new-born who died 48 hours after birth. This malformation consisted in a total aplasia of the corpus cavernosum and bulbus penis with a fusiforme dilatation of the anterior urethra. The malformation was associated with an anal imperforation, bilateral cryptorchidism and renal hypoplasia.
|
4f3f7c78-1109-4f7d-a824-5e675406277b
| 0 |
On the mechanism of action of clozapine on the adrenergic neurone. 1 The antipsychotic drug, clozapine, lowered noradrenaline and metaraminol (MA) concentrations in the rat heart. This action was blocked by the presence of a ganglionic blocking drug. 2 Other alpha-adrenoceptor blocking drugs (phenoxybenzamine, phentolamine) did not significantly lower heart amine concentrations.
|
4f3f7c78-1109-4f7d-a824-5e675406277b
| 1 |
An inhibitor of neuronal amine uptake (desipramine) caused only a slight lowering. The combination of phentolamine and desipramine showed considerable activity, and this action was blocked by ganglionic blockade. 3 Clozapine had little or no action in blocking amine uptake, yet greatly potentiated amine release caused by the phentolamine-desipramine combination.
|
4f3f7c78-1109-4f7d-a824-5e675406277b
| 2 |
4 Other antipsychotic drugs (haloperidol, chlorpromazine, thioridazine) or other agents (propranolol, atropine) did not share this action of clozapine. 5 Ganglionic blockade markedly delayed amine release induced by reserpine administration. 6 It is suggested that clozapine may have an incomplete reserpine-like effect specifically on the adrenergic neurone, facilitating impulse-induced amine release.
|
39bf31f8-bafd-49b5-9061-06f68e7c0254
| 0 |
Effect of SAS (a new 10-N-acylaminophenothiazine) on gastric secretion and ulceration in rats. The antiulcer and antisecretory activity of 2-chloro-10-[4'(N-beta-hydroxyethyl) piperazinyl-1'] acetylphenothiazine (SAS) has been investigated. At 10 and 20 mg/kg (s.c.) the drug was found to possess potent antigastric secretory and antiulcer activity (both in shay and stress ulcers) and did not exhibit any peripheral parasympathetic blocking activity. The pronounced antispasmodic activity of SAS was nonspecific rather than a specific parasympatholytic effect.
|
48d7d94e-dddf-45f8-996a-3d4f3a17553c
| 0 |
Histamine H2-receptors in the human peripheral circulation. Histamine (10 mug/min for 3 min) infused into the brachial artery caused an increase in forearm blood flow which was reduced by mepyramine (25 mg). This effect was most marked in the first minute of the infusion. Metiamide (25 mg) had no effect on the dilatation during the infusion but caused a quicker return of flow to the resting level.
|
48d7d94e-dddf-45f8-996a-3d4f3a17553c
| 1 |
The response was abolished when both drugs were given in combination. It is concluded that the response is initiated mainly by stimulation of H1-receptors and maintained by H1- and H2-receptors; continued activity of H2-receptors may account for the slow return of flow to the pre-infusional level.
|
be6f0052-bd2c-4aa2-b99e-e34cb764edf8
| 0 |
A trial of fenfluramine in the treatment of the chronic alcoholic patient. In a double blind trial, 50 male chronic alcoholic patients were treated with either fenfluramine in a dose of 60 mg or 120 mg daily, or with identically prepared placebo tablets. Patients were interviewed on admission to the trial and then at four-weekly intervals for a period of one year and blood levels of delta-aminolaevulinic acid dehydratase (ALAD) and gamma-glutamyl transpeptidase (gammaGT) and fenfluramine were determined.
|
be6f0052-bd2c-4aa2-b99e-e34cb764edf8
| 1 |
The efficacy of fenfluramine at the two dose levels was compared with placebo on the basis of the number of lapses indicated by the clinical history and also by alterations in the biochemical indices. Twenty-seven patients completed the period of observation, there being 9 in each of the three groups.
|
be6f0052-bd2c-4aa2-b99e-e34cb764edf8
| 2 |
Those receiving 120 mg fenfluramine daily showed significantly fewer lapses than either of the other two groups (p less than 0-01) on biochemical but not on clinical criteria. Overall assessment revealed that 3 of the 9 patients receiving the high dose of fenfluramine had a good result during the period of the trial, but there were none in the 60 mg group or in those receiving placebo.
|
be6f0052-bd2c-4aa2-b99e-e34cb764edf8
| 3 |
More extensive trials of fenfluramine in the treatment of chronic alcoholism are indicated.
|
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