[Proteinases with various substrate specificities in structural studies of yeast cell walls]. / Proteinazy s razlichnoi substratnoi spetsifichnost'iu v strukturnykh issledovaniiakh kletochnoi stenki drozhzhei.

Different proteins are revealed in cell wall of yeast cells Candida utilis by means of specific proteolysis with subtilisins TV and 72, trypsin and purified collagenase of Clostridium histolyticum. Some of them were characterized by resistance to trypsin and sensitivity to subtilisin TV. In young cells this group is represented essentially by a protein of 33 kD, which appears to be one of the structural proteins, binding fibrillae of carbohydrate. Other proteins proved to be sensitive to both trypsin and subtilisin. Among these proteins a protein with mol. mass 80 kD was revealed; its sensitivity to extremely specific hydrolysis by bacterial collagenase suggests it to contain amino acid sequences characteristic for collagens of higher eukaryotes.

[Preparation of recombinant metastazin and characteristics of it]. / Poluchenie rekombinantnogo metastazina i ego kharakteristika.

The recombinant mts-1 protein has been obtained with the use of the pMAL-c expression vector. This protein was shown to bind calcium ions and interact with melittin, a polypeptide from bee venom.

[Identification of the gene for the immunodominant p35 protein from vaccinia virus]. / Identifikatsiia gena immunodominantnogo belka p35 virusa ospovaktsiny.

A major immunodominant envelope protein p35 of vaccina virus was purified by means of extraction from virions with detergent NP-40. The protein was cleaved with CNBr, four homogenous peptides were isolated and their N-terminal amino acid sequences were determined. Computer search in a protein sequences data bank revealed that the immunodominant protein p35 of vaccinia virus is encoded by H3 gene in HindIII-H fragment of vaccinia virus genome.

[Interaction of a synthetic fragment of the oncoprotein p21ras with cellular proteins]. / Vzaimodeistvie sinteticheskogo fragmenta onkobelka p21ras s kletochnymi belkami.

A decapeptide corresponding to residues 35-44(-Thr-Ile-Glu-Asp-Ser-Tyr-Arg-Lys-Gln-Val-) of p21ras was synthesized. It was found that peptide causes precipitation of some proteins from the Triton X-100 lysate of NIH 3T3 EJ cells. SDS-PAGE demonstrated the presence of many proteins in this precipitate. The peptide labeled with [125I]Bolton-Hunter reagent specifically recognized four proteins of M. W. 27, 35, 50 and 85 kDa. The order of charged amino acid residues in the fragment 35-44 of p21ras is "complementary" to that of the substrate sequence of tyrosine-specific protein kinases (-Arg-X-X-Glu-Asp-X-X-Tyr-). It is suggested that p21ras proteins directly regulate phosphorylation of the target proteins of these kinases. A model for functioning of p21ras proteins predicts the presence in their structure of certain sites homologous to sequences recognizable by tyrosine-specific kinases. Indeed two such sites are present in the sequences of all p21ras proteins, namely the residues 88-92 and 104-108.

[Topography of cysteine residues in DNA-dependent RNA-polymerase]. / Topografiia ostatkov tsisteina v DNK-zavisimoi RNK-polimeraze.

Chemical modification of DNA-dependent RNA polymerase with monoiod-[14C]acetic acid and N-[14C]ethylmaleimide has been carried out and position of superficial and functionally important as well as enzymatically non-significant, exposed cysteine residues have been localised in the enzyme. Topography of cysteine residues in the RNA-polymerase alpha-subunit is thoroughly studied. The results are summarized in a model.

[The role of sulfhydryl groups in the functioning of DNA-dependent RNA-polymerase]. / Rol' sul'fgidril'nykh grupp v funktsionirovanii DNK-zavisimoi RNK-polimerazy.

Sulfhydryl groups of Escherichia coli DNA-dependent RNA polymerase were chemically modified with alkylating and mercuric-containing compounds. Iodoacetic acid and iodoacetamide were shown not to affect the enzymatic activity, whereas N-ethylmaleimide and mercuric-containing compounds completely inhibit the RNA synthesis. RNA polymerase modified with mercuric ions looses the ability of binding with promoter--containing DNA fragments. Moreover, mercuric ions inhibit the RNA elongation stage. Suggestion is made the Cys residues of RNA polymerase play a key role in double-stranded DNA unwinding. It is shown that SH-groups of beta- and beta'-subunits participate in the binding with double-stranded fragments of DNA.

[RNA polymerase-rifamycin. A molecular model of inhibition]. / RNK-polimeraza-rifamitsin. Molekuliarnaia model' ingibirovaniia.

By fluorimetric titration of Rifs (E. coli B) and Rifr (E. coli rpoB255) RNA polymerases with rifamycin, the mutant polymerase was demonstrated to bind rifamycin. A comparison of spatial structures of rifamycin and dinucleotide fragment of RNA in the hybrid with DNA revealed their similarity. Taking into account this structural similarity and also the fact that two phosphodiester bonds can be formed by RNA polymerase in the presence of rifamycin, a model for the inhibition mode was proposed. According to this model, rifamycin occupies the place of two terminal nucleotides of synthesized, but not translocated pentanucleotide in the transcribing complex. Asp-516 of the wild type beta-subunit was assumed to form a hydrogen bond with the rifamycin C(23) hydroxyl group. On the base of this model, reduced "cycling" synthesis of tetra-, penta-... up to decanucleotides by the Rifr RNA polymerase, in comparison with Rifs, was predicted.