Biomedical subjects

V M Stepanov

Publications and source records attributed to V M Stepanov.

At least 163 records · Page 9Linked to original sources

PubMed1976

[Biospecific chromatography of chymosin].

Chromatography of commercial rennet was studied on biospecific sorbents obtained by means of coupling of activated Sepharose 4B with epsilon-aminocapronyl-D-phenylalanine methyl ester and amide, epsilon-aminocapronyl-L-phenylalanyl-D-phenylalanine methyl ester, gramicidin S and N-2,4-dinitrophenylhexamethylenediamine. A mixture of two similar on their specificity enzymes chymosin and bovine pepsin was isolated from rennet by the chromatography on these sorbents. The individual enzymes might be isolated by chromatography on immobilized ribonuclease at pH 3,0, or by means of electrofocusing in pH gradient 4-6. Coloured inhibitor of acid proteases, N-diazoacetyl-N'-2,4-dinitrophenyl-ethylenediamine (DDE) is found to inactivate chymosin at pH 5,6 in the presence of Cu2+,one residue of the inhibitor being attached to the enzyme molecule. Unlike pig pepsin, chymosin is not inhibited with DDE at pH 4,7 and at the enzyme:DDE:Cu2+ ratio being 1:40:40. a synthesis of peptide sorbents is described.

Chromatography↗

PubMed1976

[Equine pepsins].

6 forms of pepsin are found in horse gastric juice. Amino acid sequence is determined of N-terminal (most variable) part of polypeptide chain of main pepsin components. Equine pepsines, which have pI 2.1 and 2.3, are found to have identical amino acid sequence at least for 31 amino acid residues. The same sequence is observed in the component with pI 2.6 for 10 first residues. The sequence of equine pepsin with pI 3.2 has 3 substitutions for 33 amino acids, when compared with pepsines having pI 2.1 and 2.3. The forms of equine pepsin studied are more similar than the other isoenzyme pair, human pepsin and gastricsin.

Amino Acid Sequence↗

PubMed1976

[Biospecific chromatography of acid proteinases. The role of ionic and hydrophobic interactions].

Pepsin chromatography was studied on peptide ligand sorbents, differing in the length of the polypeptide chains, ionogenic groups and the nature of hydrophobic side groups. Pepsin sorption was found to be dependent of a specific interaction of the substrate analogs with the enzyme and ionic interactions with the matrix and ionogenic groups of the ligand. Non-specific hydrophobic interactions of the enzyme and the ligand have little effect on the sorption. Efficient methods for the isolation of pepsin and separation of the mixture of bovine chymosin and pepsin are described.

Animals↗

PubMed1976

[Biospecific chromatography of Bacillus subtilis metalloendoproteinase and detection of multiple forms of the enzyme].

Metalloendoproteinase was isolated from protosubtilin, i.e. a mixture of enzymes produced by Bacillus subtilis, during adsorption on activated carbon and a subsequent biospecific chromatography on DNP--hexamethylene diamine--Sepharose 4B and gramicidin S--Sepharose 4B. The molecular weight of the enzyme estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate was found to be 36.000. The preparation isolated contained four molecular forms of the enzyme, each splitting DNP-Gly-Gly-Val-Arg. It is shown that thermolysine, purified by biospecific chromatography, consists of three molecular forms. The amino acid composition of metalloendoproteinase was established.

Amino Acids↗

PubMed1976

[Isolation and properties of the acid carboxypeptidase of Aspergillus oryzae].

Caboxypeptidase with pH optimum 4--5 for peptide substrates is isolated from "oryzine", the enzyme mixture produced by Aspergillus oryzae, by means of successive salt fractionation, Sephadex G-75 gel filtration, chromatography on amberlite IRC-50, hydroxylapatite, DEAE-cellulose and polyacrylamide gel electrophoresis. Its molecular weight, as determined by means of polyacrylamide gel electrophoresis in the presence of sodium dolecylsulphate, was found to be 37 000. The enzyme has a broad substrate specificity and does not possess dipeptidase and esterase activities. Acid carboxypeptidase from Asp. oryzae is not a metalloenzyme, it is inactivated by specific inhibitors of serine proteases and by compounds blocking SH-groups. The enzyme is suggested to contain functionally important serine and cysteine residues and to be acid carboxipeptidase.

Aspergillus↗

PubMed1975

Chromatography of acid proteinases and chymotrypsin on a sorbent containing 2,4-dinitrophenyl residues.

A sorbent obtained by treatment of cyanogen bromide-activated Sepharose 4B with mono-N-DNP-hexamethylenediamine has been shown to be effective in the affinity chromatography of pepsin, pepsinogen and acid proteinase from Aspergillus awamori. It is considered that 2,4-dinitrophenyl residues of the sorbent interact specifically with the hydrophobic zone of the enzyme, which may belong to the substrate binding site. The chromatography of chymotrypsin on the same sorbent supports this assumption.

Absorption↗

PubMed1974