[The accumulation of proteins with chitinase activity in the culture media of the parent and mutant Serratia marcescens strain grown in the presence of mitomycin C]. / Dinamika nakopleniia belkov s khitinaznoi aktivnost'iu v kul'tural'noi zhidkosti mutantnogo shtamma i iskhodnogo shtamma Serratia marcescens v prisutstvii mitomitsina C.

The study of the accumulation pattern of extracellular proteins with chitinase activity in the parent Serratia marcescens strain Bú 211 (ATCC 9986) grown in the presence of mitomycin C and its mutant strain with the constitutive synthesis of chitinases grown in the absence of the inducer showed that chitinase activity appeared in the culture liquids of both strains at the end of the exponential phase (4 h of growth) and reached a maximum in the stationary phase (18-20 h of growth). The analysis of the culture liquids (12 h of growth) by denaturing electrophoresis in PAAG followed by the protein renaturation step revealed the presence of four extracellular proteins with chitinase activity and molecular masses of 21, 38, 52, and 58 kDa.

[Phosphatase from Proteus mirabilis]. / Fosfataza Proteus mirabilis.

Cell-free preparations of Proteus mirabilis contained a phosphatase (EC 3.1.3.1), whose activity surpassed that of alkaline phosphatase from Escherichia coli. Phosphatase was also found in the culture liquid of P. mirabilis. The composition of proteins displaying enzyme activity was assayed by polyacrylamide gel electrophoresis. Enzyme synthesis was studied at various stages of bacterial growth. Biosynthesis of phosphatase in P. mirabilis (similarly to that in other bacteria) was shown to be induced under conditions of inorganic phosphate deficiency in the medium.

[Endonuclease from Proteus mirabilis]. / Endonukleaza Proteus mirabilis.

Two isoforms of nuclease displaying DNase and RNase activities were found in the culture liquid and periplasm of Proteus mirabilis. The enzyme was isolated from the periplasm and then purified to a functionally homogeneous state. The nuclease was equally potent in cleaving denatured and native DNAs by the endonuclease mechanism and was designated Pm endonuclease. The endonuclease was shown to be a temperature-dependent enzyme with a pH optimum of 10.4-10.6, requiring the presence of bivalent metal ions and inhibited by citrate and ethylenediaminetetraacetate.

[Biosynthesis of Proteus mirabilis nuclease]. / Biosintez nukleazy Proteus mirabilis.

The culture liquid and periplasm of Proteus mirabilis contained nuclease, an enzyme with DNase and RNase activities. The nuclease was most actively synthesized in the early exponential and stationary growth phases. Nuclease synthesis was regulated by nucleic acids (induction by substrate) and inorganic phosphate (end-product inhibition). The synthesis and secretion of nuclease by P. mirabilis was induced by mitomycin C, an inducer of the SOS functions of cells. This suggests the involvement of SOS-response proteins in the regulation of nuclease synthesis.

Biosynthesis of endochitinase of Serratia marcescens.

The growth of a mutant strain of Serratia marcescens with high chitinase activity and the biosynthesis of endochitinase by this strain were investigated. The study was carried out using semisynthetic culture medium without inducers and culture medium containing colloidal chitin as a sole nitrogen and carbon source, with and without mitomycin C. The mutant strain, unlike the native one, was shown to produce endochitinase and to secrete the enzyme into the medium during the growth on culture medium without the inducers, chitin and mitomycin C. During growth on the medium with chitin the mutant strain differed from the native one with a short lag-phase of growth, the early appearance of endochitinase in the culture liquid and a high level of endochitinase activity. The difference between the strains disappeared after the addition of mitomycin C, an inducer of the cell SOS-response, to the culture medium containing chitin. Specific endochitinase activity of S. marcescens mutant strain grown on various culture media had two maxima, namely at the beginning and at the end of the stationary phase. Mitomycin C increased the specific activity in a second peak of endochitinase activity during the growth of the mutant strain.

[Effect of nalidixic acid and mitomycin C on growth and biosynthesis of extracellular proteins by Serratia marcescens]. / Vliianie nalidiksovoi kisloty i mitomitsina C na rost i biosintez vnekletochnykh belkov Serratia marcescens.

The effect of various concentrations of nalidixic acid and mitomycin C on the dynamics of growth of Serratia marcescens and synthesis of endonuclease and other extracellular enzymes by it was studied. The synthesis of extracellular endonuclease was induced during inhibition of the cell division under the effect of nalidixic acid and mitomycin C. The induction of the endonuclease synthesis preceded the start of the division of the resistant cells which overcame the phase of the population retarded growth. The fermentation broth of the cells exposed to nalidixic acid and mitomycin C contained increased amounts of protein and possessed higher activities of chitin phosphodiesterase and phosphatase. It was shown by PAAG-electrophoresis with sodium dodecyl sulphate that the pattern of the extracellular proteins of S. marcescens undergone quantitative and qualitative changes under the effect of nalidixic acid and mitomycin C.

[Induction of synthesis of extracellular DNAase from Proteus mirabilis under the effect of compounds, blocking DNA replication]. / Induktsiia sinteza vnekletochnoi DNKazy Proteus mirabilis pod vliianiem soedinenii, blokiruiushchikh replikatsiiu DNK.

The effects of mitomycin C and nalidixic acid on the biosynthesis of extracellular endodeoxyribonuclease in Proteus mirabilis have been studied. The presence of both antibiotics in the periodic and short-time cultures of washed off cells has increased both the activity of the DNAse and protein yield in cultural liquid and bacterial cells. PAGE-electrophoresis has shown the effect of mitomycin C to increase or induce the synthesis a large number of Proteus mirabilis extracellular proteins.

[Effect of mitomycin on the biosynthesis of extracellular endonuclease by Serratia marcescens]. / Vliianie mitomitsina na biosintez vnekletochnoi éndonukleazy Serratia marcescens.

The effect of mitomycin C on extracellular endonuclease activity of Serratia marcescens was studied. It was shown that in a concentration of 0.02-1.0 micrograms/ml, mitomycin C markedly increased biosynthesis of the endonuclease by growing and washed cells, the cell productivity being increased 80-100 times. The highest increase in the cell productivity was observed when mitomycin C was added to the cells at the end of the growth exponential phase. The increase in the activity of the extracellular endonuclease was due to the de novo synthesis of the enzyme since it was inhibited by chloramphenicol.

[Deoxyribonuclease from Corynebacterium diphtheriae: dynamics of synthesis and properties]. / Dezoksiribonukleaza difteriinykh bakterii: dinamika obrazovaniia i nekotorye svoistva.

Diphtheritic bacteria of PW-8 Massachusetts strain produced into cultural medium only one nucleotidase--endoDNAase. The enzyme was synthesized by the cells during the exponential phase of growth. The DNAase was purified 500-fold and exhibited properties specific to neutral-alkaline DNAases (pH optimum about 7.5, absolute requirements for Me2+, single-step mechanism of substrate hydrolysis). The following properties were typical for the enzyme: absence of distinct specificity to structure of bases surrounding the hydrolyzed bond, formation of 5'-end phosphate groups and slightly higher preference to denatured DNA.

[Deoxyribonuclease of Proteus mirabilis]. / Dezoksiribonukleaza Proteus mirabilis.

DNAase was isolated and purified from cell-free extracts of Proteus mirabilis by means of fractionation with ammonium sulfate and CM cellulose chromatography. The enzyme exhibited the endonuclease specificity with DNA as a substrate, split off the native DNA by the "single-strike" mechanism, had a pH optimum in alkaline zone, required Me2+ and was inhibited by tRNA. The highest specific activity and the specific rate of the enzyme synthesis were found at lag phase, before the exponential phase of the cell population growth. Microorganisms of Proteus and Salmonella genera had the highest enzymatic activity in cell-free extracts as compared with other enterobacteria. Possible biological functions of the enzyme are discussed.

[Intracellular nucleodepolymerase of bacteria, representatives of the Proteus and Providencia groups. Its isolation and properties]. / Vnutrikletochnye nukleodepolimerazy bakterii--predstavitelei gruppy Proteus i Providencia. Poluchenie i nekotorye svoistva

High activity of enzymes, splitting native, denaturated DNA, deoxyribooligonucleotides and RNA, was observed in cell free extracts of bacteria--representatives of 5 strains of Proteus-Providencia. Some properties of nucleases were studied in cell free extracts. In the bacteria studied DNAases were thermolabile proteins, which were completely inactivated at 50-60 degrees, RNAases were more thermostable. The pH optima of the DNAases were at pH 9.0-11.0 in cell free system; RNAases were maximally active at pH 8.0-9.0