Showing papers in "Ukraïns'kyĭ biokhimichnyĭ zhurnal in 1975"

Biosynthesis of flavins and its regulation in the yeast Pichia guilliermondii

Abstract: The nature of riboflavin precursors was studied in the yeast Pichia guilliermondii. By means of mutants with blocked GMP-synthetase the purine precursors of riboflavin were shown to belong to guanylic compounds. Accumulation of 2,4,5-triamino-6-oxypyrimidine, 2,5-diamino-6-oxy-4-ribitylaminopyrimidine, 2,6-dioxy-5-amino-4-ribitylaminopyrimidine (DOARAP) and 6,7-dimethyl-8-ribityllumasine occurs in the riboflavin-deficient mutants divided into five biochemical groups. This fact evidences for identity of riboflavin precursors in the yeast P. guilliermondii and Saccharomyces cerevisiae. Synthesis of DOARAP by the washed off cells of the mutants with the blocked lumasine synthetase is strongly inhibited by riboflavin; cycloheximide in the absence of riboflavin has no effect on this process. Consequently, flavinogenesis in P. guilliermondii is regulated according to the type of negative feedback by means of retroinhibition mechanism. A change in the content of flavins in the cells has no effect on synthesis of riboflavin synthetase; at the same time iron deficiency in the cells evokes derepression of this enzyme. Incubation of the cells rich in iron with o-phenantroline or alpha, alpha'-dipyridyl also causes derepression of riboflavin synthetase which is inhibited by cycloheximide. A deficiency of hem in the mutants which need epsilon-aminolevulinic acid does not affect the riboflavinsynthetase activity of the cells. Evidently, in P. guilliermondii a certain form of nonheminic iron might take part in regulating synthesis of riboflavin synthetase and other enzymes participating in riboflavin biosynthesis. Riboflavin overproduction is established to require formation of purines de novo. With the absence of flavinogenesis enzymes derepression a genetic disturbance in regulation of purinic nucleotides biosynthesis results in stimulation of flavinogenesis. The properties were studied for 680 time purified riboflavinkinase from cells of P. guilliermondii as well as for three phosphatases possessing the optimum of the activity at pH 3.5, 5.5 and 8.6, which ARE ABLE OF HYDROLYSING FMN. A change in the content of flavins and iron in the cells has no effect on the activity of riboflavinkinase in this species. Evidently, the mechanisms of riboflavin and flavin nucleotides biosynthesis regulation would be different in P. guilliermondii.

Change in conformation of histones F 2a and F 2b in solutions of different ionic strength

Abstract: A change was studied in the differential absorption spectra and fluorescence quantum yield of histones F2a and F2b with the ionic strength varies It is shown that the structure of the histone F2a molecule stops changing with an increase in the concentration of NaCl up to 05 M In the histone F2b molecule the conformational changes occur with the NaCl concentration less than 10 M The conformation change results in formation of hydrophobic areas on the histone surface, which intensifies the histone-histone interaction The role of the histone conformational changes for regulation of gene activity is discussed

Determination of riboflavin kinase activity in yeast

Abstract: It is established that the main reason of the riboflavin kinase (RFK, EC 2.7.1.26) low specific activity in the cell-free extracts of the yeast Pichia guillermondii Wickerham ATCC 9058 is the presence of alkaline phosphatase (EC 3.1.3.1), effectively destructing flaven mononucleotide. By chromatography of the cell-free extracts of P. guillermondii on DEAE-Sephadex A-50, CM-Sphadex C-50, CM-cellulose, Sephadexes G-75 and G-100 RFK and alkaline phosphatase may be separated completely. Any of these procedures results in a several times increase of the RFK activity as compared with the initial preparation. One failed to obtain a similar effect by fractionation of the extracts with amminium sulphate and by hydroxylapatite chromatography. A simple method is developed for determining the activity of RFK in the cell-free extracts of yeast on the basis of negative adsorption of this enzyme on DEAE-Sephadex A-50. A selective inhibition of alkaline phosphatase by ions Be2+ and F- yields a less satisfactory result. The data are presented on the PFK activity of certain species of flavinogenic (Pichia guillermondii, Torulopsis camdida) and non-flavinogenic (Pichia ohmeri, Candida utilis, Saccharomyces cervisiae) yeast.

[Enzymes of glycolysis and pentosephosphate shunt during early embryogenesis of the loach and the effect of glucose, lactate and fumarate on fertilized oocytes].

Abstract: The regularities for changes were established in activity of hexokinase, glucokinase, glucosephosphate-isomerase, phosphofructokinase and glucose-6-phosphate dehydrogenaseduring the early development of loach (Misgurnus fossilis). It was found that a 30-minute incubation of fertilized loach eggs in the lactate or fumarate solutions decreases the glucokinase activity in the embryos of 3, 6, 9, 12, 15, 18 and 24 hours of their development, while the inhibitory effect of glucose on the enzyme activity is pronounced only after 18 and 24 hours of the development. A significant increase in the hexokinase and glucose-6-phosphate dehydrogenase activities under the above-mentioned conditions is observed only under the effect of glucose 9 and 6 and 9 hours, respectively, after fertilization. The glucose phosphate isomerase and phosphofructokinase activites under the effect of used compounds undergo no changes during the primary stages of embryogenesis.

Study of the soluble proteins of the skin of young cattle in the presence of ultraviolet irradiation in vivo and in vitro

Abstract: The effect of ultraviolet irradiation on the quantity of soluble proteins in skin and content of SH-groups in them, immunoelectrophoretic, electrophoretic properties and amino acid composition of soluble skin proteins was studied under ultraviolet irradiation of calfs and solutions of those proteins in vitro. Ultraviolet rays are established to affect the total content of soluble proteins and SH-groups under ultraviolet irradiation of the animals and these proteins solutions in vitro, but the character of the obtained changes is different in both cases. The quantity of soluble proteins in the animal skin depends on the irradiation frequency. In the composition of the calf skin soluble proteins 14 proteins were found immunologically similar to the blood serum proteins of these animals. Ultraviolet irradiation of the soluble skin proteins in vivo and in vitro does not affect their amino acid composition.

[Specific substances of the thymus reacting with thymus-dependant antigens].

Abstract: A fraction was isolated from the sulphate extract of rats and calfs thymus. This fraction reacts with sheep erythrocytes and rabbits IgG in the agglutination test. An identical fraction from the rats spleen and liver is not active in the same concentration. Active substance was purified by affinity chromatography on IgG cellulose column. The absorption spectrum of the purified substance in 220-300 nm region was studied at pH 7. This substance has not the absorption maxima in 280 nm. The sedimentation constant of the crude preparation is approximately 1.7 s. It supposed, that this substance is a specifical receptor of thymic cells.

[Krebs cycle in tissue of rats subjected to combined effect of hypercapnia, hypoxia and cooling].

Abstract: The content of the Krebs cycle substrates and activity of dehydrogenases corresponding to them were studied in the brain and myocardium tissues of the non-linear male rats adapted to acute hypoxia under conditions of the altered gas medium. The content of malate and succinic acid was studied in the liver and skeletal muscles only. In the brain the total activity of malate dehydrogenase (MDH, EC 1.1.1.37, 1.1.1.39) alpha-ketoglutarate dehydrogenase (KDH, EC 1.2.4.2) pyruvate dehydrogenase (PDH, EC 1.2.4.1) and isocitrate dehydrogenase (ICDH, EC 1.1.1.41-42) is shown to be decreased and kept to be lowered in all the periods of the study. No essential shifts in the activity of these dehydrogenases were found in the myocardium. The activity of succinate dehydrogenase (SDH, EC 1.3.99.1) in both tissues lowers 48 h after the effect of the mentioned factors. Simultaneously the greatest changes in the level of the substrates were observed in the myocardium, in the brain they were less developed. In the liver the content of malate increases without pronounced changes in the amount of succinic acid and in the skeletal muscles the level of malate and succinic acid lowers.

[Comparative characteristics of catalase from the fungus Penicillium vitale, which is synthesized under different nutritional conditions]

Abstract: A comparative study of properties (absorption spectra, thermostability, pH optimum, polyacrylamide gel electrophoresis, DEAE-cellulose separation) and structure (amino acid composition, finger-prints, carbohydrate composition) was performed for P. vitale catalase synthesized under different medium conditions. In all cases the results were similar. The only difference occured in the amount of synthesized proteins. A conclusion is drawn that under different nourishing conditions of the fungus the properties and structure of the catalase are unchanged, but the regulatory mechanisms of catalase and glucosooxidate synthesis undergo changes.

[Comparative study in structure of myoglobins in semiaquatic animals: Castor fiber, Ondatra Zibethica, Lutra lutra].

Abstract: A degree of similarity in the structure of myoglobins in the semiaquatic animals (beaver, muskrat, otter) is shown by the finger-print method with the determination of amino acids content in peptides. It is established that about 2/3 of the acid sequence in the investigated myoglobins are invariable. An assumption is advanced that these regions of the structure are of most importance in the functional respect.

Influence of denervation of the liver on its level of nucleic acids and free adenine nucleotides

Abstract: It is established that liver denervation is accompanied with a significant increase of DNA content on the 10, 20 and 30th day after operation: 19, 22 and 25%, respectively. The 12% rise on the average in RNA content is observed on the 10th day. This level is preserved during the following days after denervation. The changes in the content of free adenine nucleotides are contrary. The decrease in ATP quantity, which is insignificant on the 10th day, makes progress and reaches 20% on the 20th day. The decrease in ADP is 13%, the content of AMP remains practically unchanged. The obtained data evidence for the participation of the nervous system in maintaining the normal level of poly- and mononucleotides, specific for the liver.

Gelatin from bone collagen hydrolyzed with Streptomyces griseus protease and its properties

Abstract: Gelatin melting from bone collagen previously hydrolyzed with the Str. griseus protease was studied as dependent on the medium temperature. The properties of this gelatin were compared with those of others melted from collagen previously extracted with alkali. Gelatin obtained by using the Str. griseus protease has the average molecular weight of 63 400 characteristic viscosity of 0.22, it contains 10.6% of oxyproline and 0.06% of free carbohydrates. By a degree of heterogeneity the preparation obtained does not differ from those used for the comparison.

Hydrolysis of insoluble collagen of bull bones by Streptomyces griseus crystalline protease

Abstract: Hydrolysis of collagen was studied in the bull bone tissues by the Str. griseus crystalline protease. The amount of collagen hydrolyzed by it composed 6.6% and 16% after 4-hour and 6-hour hydrolysis, respectively. When the enzyme:substrate ratio is 1:50 hydrolysis proceeds most intensively; with a decrease in the ratio up to 1:1000 the average amount of peptides increase from 2.6 up to 4 amino acidic residua, respectively. Under conditions of denaturated collagen hydrolysis the content of hydroxyproline in solution as compared with the native one increases; in this case the links with the presence of imino-acids are easier to split, the more resistant being those formed by hydroxyproline. Within the limit of 20-45 degrees C hydrolysis of protein intensifies with a temperature rise. Within the pH range of 5.0-11.0 the maximal amount of alpha- NH2-groups and hydroxyproline is observed at pH 8.5, the minimal--at PH 5.0. Hydroxyproline in the composition of peptides appears at the beginning of hydrolysis whereas the free one of enzymes of the longer effect 24 h after the beginning of the experiment composes 12.2% of its total content in the solved products. In the insoluble part of the substrate after 3-hour hydrolysis tyrosine composes less than 25% of its initial amount in protein whereas phenyl alanine--over 70%. After 6-hour hydrolysis the solved part of the system contains about 30% of alanine and 8.9 and 6% of glycine, proline and hydroxyproline, respectively.

[Swelling and contraction of rat liver mitochondria under the effect of hexachlorocyclohexane gamma-isomer and polychlorocamphene].

Abstract: Swelling and contraction of the rat liver mitochondria were studied as affected by chloroorganic pesticides of hexachlorocyclohexane gamma-isomer (gamma-HCCH) and polychlorocamphene (PCC). Administration for two days of gamma-HCCH in a dose of 34 mg/kg and PCC in a dose of 48 mg/kg established to ccause swelling of the liver mitochindria in vivo, a decrease in their ability to swelling in KCl and KH2PO4 and to contraction with addition of ATP. When gamma-HCCH is administered daily for six months in a dose of 1.7 mg/kg the indices under study rise and in case of PCC analogous adninistration in a dose of 2.4 mg/kg-- the drop. The found differince in the effect of the mentioned preparations when they are introduced to the animal organism for a long time might be connected with singularities in their cumulative properties.