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Biomedical subjects

V N Orekhovich

Publications and source records attributed to V N Orekhovich.

At least 19 recordsLinked to original sources
PubMed1990

[The peptidase activity of a cellular extract of the causative agent of plague].

Peptidase activity of Yersinia pestis cell extract was studied by the hydrolysis of synthetic and some natural substrates, as well as the hydrolysis of fluorogenic aminopeptidase substrates. All peptides and fluorogenic substrates under test were split by Y. pestis cell extract, the splitting of alanylaminopeptidase substrate being linked with at least two enzymes of this cell extract.

Aminopeptidases↗
PubMed1989

[Study on the effect of some group-specific agents on clostridiopeptidase].

The interaction of clostridiopeptidase of Clostridium histolyticum with EDC, TNM and MA, the specific reagents for COOH-groups, tyrosine and lysine residues was studied. It was shown that at pH 6.0 EDC inactivates the enzyme. The inactivation process follows the pseudo-first order kinetics and is described by a second order rate constant equal to 1 M-1 min-1. The synthetic substrate does not prevent, in practical terms, the enzyme inactivation by EDC. At pH 8.0 TNM modifies about 19 tyrosine residues in the clostridiopeptidase molecule which is accompanied by marked inhibition of the enzyme activity (down to 70-90%). In this case, the inactivation process is not described by simple pseudo-first order kinetics but is characterized by two steps (fast and slow) with second order rate constants of approximately 14 and 3.5 M-1 min-1, respectively. The synthetic substrate partly prevents the inactivation of the enzyme by TNM and protects 11 tyrosine residues. The MA-induced incorporation of 13 +/- 3 maleyl groups into the clostridiopeptidase molecule in partially prevented by the synthetic substrate with protects the enzyme against inactivation. The data obtained suggest that lysine residues are seemingly included into the active center of clostridiopeptidase, whereas tyrosine residues provide for the maintenance of active conformation of the enzyme.

Collagen↗
PubMed1989

[Isolation and purification of biopolymers using an affinity chromatography method. IX. Preparation, properties and use of affinity adsorbents with immobilized polypeptide fragments of collagen].

Synthesis and properties of new affinity adsorbents with immobilized polypeptide fragments of collagen molecule (alpha-chains, beta-components, cyanogen bromide peptides) were described. Adsorbents with alpha-chains and alpha 1CB7-peptide had fibronectin binding capacity 1.5-2.0 times higher than commercial gelatin-Sepharose. Commercial production of highly purified fibronectin from human plasma using affinity chromatography on immobilized individual alpha-chains of collagen was developed.

Animals↗
PubMed1987

[Induction of blood plasma carboxycathepsin (angiotensin I-converting enzyme) in normo- and hypertensive rats in response to a single administration of captopril].

The experiments were carried out to elucidate the effect of carboxycathepsin (CC) activity inhibition by a specific inhibitor--captopril--on plasma enzyme concentration in normotensive rats and rats with renovascular hypertension. A single oral administration of captopril (10 mg/kg body weight) produced an increase in CC concentration in both hypertensive and sodium-depleted normotensive rats with a parallel decrease in arterial pressure, but had no effect on sodium-repleted normotensive rats. It is suggested that the increase in plasma CC concentration is a compensatory response to the inhibition of CC activity by captopril; it is also possible that the increase observed reflects the state of renin-angiotensin system.

Animals↗
PubMed1987

[Inactivation of blood plasma alpha 1-proteinase inhibitor as affected by 2 splenic thiol proteinases active in a neutral medium].

It has been found that two active in neutral medium thiol proteinases from bovine spleen, cathepsin L and cathepsin H, bring about rapid and irreversible inactivation of alpha 1-proteinase inhibitor (alpha 1PI)--one of the major plasma inhibitors of serine proteinases. The activity of the enzymes studied did not change upon the interaction with alpha 1PI. With stoichiometric proteinase/inhibitor ratio, the inactivation of alpha 1PI under the effect of cathepsin L was instantaneous, while under the effect of cathepsin H it occurred within 30-60 min. The products of alpha 1PI inactivation had an inhibitory effect on the rate of its reaction with cathepsin L. alpha 1PI inactivation under the action of cathepsin L and cathepsin H was accompanied by the decrease in the molecular mass of the inhibitor from 54 kDA to 46 kDa. This was, probably, caused by the hydrolysis of the peptide bond formed by NH2 group of threonine. The 46 kDa fragment did not undergo further degradation. It did not bind to immobilized trypsin but retained antigenic properties. The results obtained show that the limited proteolysis is a mechanism of the inhibitor inactivation. It is suggested that under some conditions thiol proteinases, upon their release from the cell, participate in the control of effective alpha 1PI concentration.

Animals↗
PubMed1986

[Synthesis and analysis of conformationally restricted analogs of peptide inhibitors of the angiotensin-converting enzyme].

To investigate conformations of peptide inhibitors of the angiotensin-converting enzyme in the enzyme-inhibitor complex, the synthesis, studies of inhibitory activity, and conformational calculations of analogues of bradykinin-potentiating peptides with N-methylalanine or D-alanine in place of L-proline or L-alanine residues have been carried out. All the analogues showed a sharp decrease of inhibitory activity in comparison with the natural peptides, that might be considered as an indirect confirmation of the earlier proposed "conformation of inhibition" of the above-mentioned peptides.

Amino Acid Sequence↗