It was demonstrated previously that mitochondria of higher and lower eukaryotes can synthesize, in the course of oxidative phosphorylation, not only ATP but also inorganic pyrophosphate (PPi). Two PPases were isolated from bovine heart mitochondria (soluble--PPase I and membrane--PPase II). Coupling PPase II, in contrast to PPase I, contains phosphatidyl choline, but PPase I is lipidized readily in the presence of different phospholipids. Reconstitution experiments of the PPi synthesis system have shown that after lipidization PPase I is able to incorporate into submitochondrial particles (SMP) and becomes a coupling factor for oxidation and PPi synthesis. It seems that phospholipid is indispensible for incorporation into the membrane and the manifestation of the coupling activity of the enzyme. The effect of lipids on the activity of soluble and membrane-bound pyrophosphatase was studied. It is shown that PPase II phospholipid is involved in the regulation of the hydrolase activity of the isolated enzyme. However, hydrolysis of PPi by SMP and its synthesis by mitochondria are affected by cooperative rearrangements of the entire lipid component of the membrane rather than by changes in the phase state of phosphatidyl choline contained in PPase II. An opposite response of ATP and PPi synthesis to changes in viscosity makes it likely that the viscosity of the mitochondrial inner membrane may control the levelling of these two processes in mitochondria.

Adenosine Triphosphate↗

PubMedDate not supplied

[Isolation and certain features of a polyphosphate phosphohydrolase deficient mutant of the fungus Neurospora crassa].

A polyphosphatase deficient mutant of Neurospora crassa has been isolated. The criterion for selecting the mutant was the capacity of the fungus to assimilate polyphosphates as the source of exogenous phosphorus. The mutant like the parent strain ad-6, was an adenine auxotroph but differed from the parent strain by a lower growth rate though, at the stationary stage, its biomass reached the same level as in the strain ad-6. The character of changes in the activity of polyphosphatase in the course of growth was the same in the two cultures, but the activity of the enzyme in the mutant was considerably lower at all the growth stages. The content of polyphosphate fractions with the highest molecular weight increased twofold in the mutant culture. These data suggest that there is a close metabolic and topographic correlation between polyphosphatase and the highest molecular weight fractions of polyphosphates in N. crassa.

Acid Anhydride Hydrolases↗

PubMedDate not supplied

[Fractionation of the cellulase complex of the fungus Aspergillus terreus].

A procedure for isolating a complex of extracellular cellulases from the Aspergillus terreus culture liquid using SP-Sephadex C-50 has been developed. Enzymatically and electrophoretically homogeneous preparations of cellobiase I and cellobiase II have been obtained. By means of gel-filtration their molecular weights have been estimated to be 140,000 and 67,000. Cellobiase I consists of five and cellobiase II of two polypeptide chains. Three cellulases with various ratios of endoglucanase and exoglucosidase activities have been prepared. Using polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, their molecular weights have been found to be 11,600; 10,900 and 11,200.

Aspergillus↗

PubMedDate not supplied

[Protein yield in the rehydration of dehydrated Saccharomyces cerevisiae yeast cells].

The release of proteins was studied during rehydration of Saccharomyces cerevisiae cells dehydrated using two techniques which were characterized by different survival rate. A correlation was established between the loss of proteins and the survival rate of cells after dehydration and rehydration. Proteins with a molecular mass from 6000 to 70,000 daltons (low molecular weight proteins predominating) were found in the rehydration medium by the method of disc-electrophoresis in polyacrylamide gel in the presence of sodium dodecylsulfate. Moreover, the rehydration medium exhibited the activity of certain phosphohydrolases and dehydrogenases; this finding suggests that proteins with a higher molecular weight are present in the medium.

Desiccation↗

PubMedDate not supplied

[Membrane-bound precursor of E. coli periplasmic alkaline phosphatase: isolation and some properties].

Solubilization of membrane-bound alkaline phosphatase with 0.2% tritone X-100 and its purification to the homogenous state were performed. It was shown that the membrane-bound enzyme differed from the soluble enzyme by the N-terminal sequence, was more hydrophobic and was presented by one form of enzyme as compared to the three forms of the soluble one. By its substrate specificity this enzymes approximates the first form of the periplasmic enzyme, and does not differ from it by pH optimum, thermostability and the rate of inhibition by orthophosphate.

Alkaline Phosphatase↗

PubMedDate not supplied

[Effect of cycloheximide on glucan biosynthesis in the growth process of Saccharomyces carlsbergensis yeasts].

Biosynthesis of alkali-acid-insoluble beta-glucan was studied in the course of growth of the yeast Saccharomyces carlsbergensis IBPM Y366. Synthesis of this important component of the cell wall was shown to depend on the stage of the cultural growth. The rate of 14C-glucose incorporation into the glucan fraction was maximal at the beginning and in the middle of the logarithmic growth phase. Cycloheximide, an inhibitor of protein synthesis, at a concentration of 10 micrograms/ml inhibited glucan synthesis at the beginning and by the end of the logarithmic growth phase, but stimulated synthesis of this polymer in the middle of the logarithmic phase of growth of this organism.

Cell Wall↗

PubMedDate not supplied

[Features of secretion of bacteriolytic enzymes and polysaccharides in bacteria from the Pseudomonadaceae family].

It is shown that secretion of bacteriolytic complex enzymes in a bacterium of the family Pseudomonadaceae begins in the latent and early logarithmic culture growth phases. A maximum of specific bacteriolytic activity falls in the same time interval with a maximum of specific activity of lytic proteinase L2 and muramidase. The activity of concomitant enzymes--non-specific proteinase and neutral phosphatase--peaks in the middle of the logarithmic growth phase. Secretion of exopolysaccharide into the external medium begins in the second half of the logarithmic growth phase and, thus, is not coordinated with secretion of bacteriolytic enzymes. It is shown that relative content of enzymes and polysaccharides depends upon the composition of growth medium for the producer.

Culture Media↗

PubMedDate not supplied

[Distribution in the genomes of microorganisms of fragments homologous to cDNA of chicken pro-alpha1(1) collagen].

Southern-analysis of genomic DNAs from 14 yeast species (Ascomycetes and Basidiomycetes) with alpha 1(1) chicken collagen cDNA coding for triple-helical domain as a probe, has shown that presence of genomic fragment, homologous to collagen genes of higher eucaryotes, is characteristic for yeasts. In bacterial genomes such fragments are revealed quite rarely. No collagen-like sequences has been found in known yeast proteins by computer-analysis.

Animals↗

PubMedDate not supplied

[Acid-soluble nucleotides of the phototrophic bacterium Rhodospirillum rubrum during growth in light and in darkness].

The content of acid-soluble nucleotides was different in the cells of non-sulphur purple bacterium Rhodospirillum rubrum, growing phototrophically under anaerobic conditions and aerobically under conditions of heterotrophic nutrition. The cells of the culture growing in the darkness contained more adenylic and guanylic nucleotides, and the total of reduced and oxidized NADP. The cells of the culture growing in the light contained more FMN. The cells of the "light" and "dark" cultures contained GTP dependent phosphopyruvate carboxylase (E.C. 4.1.1.32). The cells of the "light" culture, contrary to the "dark" culture, contained also pyrophosphate dependent phosphopyruvate carboxylase (E.C. 4.1.1.38).

Aerobiosis↗