[DNA-methylase Sau 3A: isolation and various properties].

DNA-methylase Sau 3A has been isolated for the first time from Staphylococcus aureus 3A cells and purified by column chromatography on phosphocellulose PII, heparin-Sepharose and blue Sepharose. The purified enzyme methylates the GATC sequence with the formation of GATm5C as can be evidenced from the protection of DNA from digestion with restrictases Sau 3A and Bam HI, the lack of the C3H3-group incorporation into Sau 3A DNA-restricts and the formation of a single methylated base m5C. Sau 3A methylase modifies only a two-filament (but not one-filament) DNA.

[Effect of various factors on the methylation of DNAse I].

The effects of NaCl, EDTA and tRNA on methylation and enzymatic properties of deoxyribonuclease I (DNase I) were investigated. The methylation was carried out by S-methylmethionine (vitamin U) in the phosphate-citric buffer pH 4.0.

[Cobalamins and tRNA methyltransferase activity in E. coli cells].

The end of the logarithmic phase of growth of E. coli 113-3 cells in a mineral medium with methylcobalamin (MeCbl) occurs 60 minutes earlier than in the case of cells grown with cyancobalamin (CNCbl). Chromatography on a Sephadex - DEAE cellulose column of the 105 000xg fractions of cell-free extracts of the cells grown in the presence of MeCbl showed both quantitative and qualitative differences.

[Vitamin U and RNA metabolism in prokaryotes].

The paper is concerned with a study of the vitamin U effect on the rate of 14C-uridine incorporation into various categories of RNA in E. coli MRE-600 cells. It is found that cells grown with vitamin U (0.

[Influence of S-methylmethionine on the metabolism of nucleic acids in Escherichia coli].

The influence of S-methylmethionine (SMM) on metabolism of nucleic acids in E. coli MRE-600 has been studied. The influence of SMM was compared with that of methionine.

[Methylcobalamin-dependent methylation of proteins during malignant degeneration].

A capacity of methylcobalamine (14CH3-B12) to methylate proteins from rat liver tissue and from Zajdela ascites hepatoma was studied. The rate of methylation using 14CH3B12 was compared with that of the universal donor of methyl groups--S-adenosyl-L-(methyl-14C[methionine], Ado-met)-14CH3-B12 methylated proteins from Zajdela ascites hepatoma 6-9-fold and proteins from liver tissue 50-60-fold more intensively as compared with Ado-met in vitro. The methylating ability of 14CH3-B12 depended on protein concentration.

[Methylation of ribonuclease and albumin by methyl cobalamin].

The capacity of methyl cobalamine (14CH3-B12) to methylate RNase and albumin in in vitro systems was studied. Under the experimental conditions, 14CH3-B12 methylated proteins about 100--1000 times more actively than S-adenosyl-methionine, a universal donor of methyl groups. The nature of buffer and pH 2 to 8 had no noticeable effect on the methylating capacity of 14CH3-B12.

[Methylation of prokaryotic RNA by S-methyl methionine in in vivo experiments].

While cultivating the E. coli 113-3 strain on the mineral medium containing S-methyl-(methyl-3H)-methionine, the incorporation of methyl groups into 4S, 16S and 23S RNA proved to be over 5 times more effective as compared with the control, when L-(methyl-3H)-methionine acted as a donor of methyl groups. The ratio of methylated components has much in common and significant differences.

[Some aspects of protein methylation].

The paper gives a review of the literature publications on protein methylation and probable donors of methyl groups. It presents experimental data demonstrating the capability of 14CH3-B12 to methylate in vitro proteins of tRNA methylases from Zajdela ascite hepatoma and rat liver as well as commercial RNase and albumin preparations.

Influence of methylcobalamin and cyanocobalamin on the neoplastic process in rats.

The effect of methylcobalamine (5.6-dimethylbenzimidazolyl-Co-methylcobamide, CH3-B12) and cyanocobalamine (5,6-dimethylbenzimidazolyly-Co-cyanocobamide, CN-B12) on the growth of Walker's carcinosarcoma and longevity of white noninbred rats with implanted Zajdela ascites hepatoma was studied. The two agents exerted a similar effect.