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V F Pozdnev

Publications and source records attributed to V F Pozdnev.

At least 19 recordsLinked to original sources
PubMed2001

Characterization of bovine atrial angiotensin-converting enzyme.

Bovine atrial angiotensin-converting enzyme (ACE) was purified to electrophoretic homogeneity. The purification procedure included ion-exchange chromatography on DEAE-Toyopearl 650M, affinity chromatography on lisinopril-agarose and gel filtration on Sephadex G-100. The bovine atrial ACE exhibited similar sensitivities to inhibition by lisinopril and captopril as lung ACE (the Ki values for the atrial and lung enzymes differed insignificantly). However, the kinetic parameters of hydrolysis of some synthetic tripeptide substrates (FA-Phe-Gly-Gly, FA-Phe-Phe-Arg, Cbz-Phe-His-Leu, Hip-His-Leu) catalyzed by bovine atrial and lung ACE varied to a greater extent. The enzymes were also characterized by some differences in activation by chloride, nitrate, and sulfate anions. These data support the hypothesis of tissue specificity of ACEs.

Animals↗
PubMed2000

Isolation and characterization of the N-domain of bovine angiotensin-converting enzyme.

A method for preparation of a catalytically active fragment of bovine lung angiotensin-converting enzyme (ACE) has been developed. It includes limited proteolysis of the full-length somatic form of the enzyme by trypsin. The resulting fragment corresponds to the N-terminal domain of angiotensin-converting enzyme. The influence of chloride and sulfate anions on the enzymatic activity of this fragment has been investigated, and kinetic parameters for hydrolysis of synthetic tripeptide substrates catalyzed by the N-domain of ACE have been determined. Comparison of these parameters with those obtained for full-length somatic bovine ACE suggests that in the bovine somatic ACE molecule active centers located in various domains may function interdependently.

Animals↗
PubMed2000

Monoamine oxidase inhibition by N-alkyloxycarbonyl derivatives of ethylene diamine.

Urethane type derivatives of ethylene diamine (EDA) were synthesized and tested as inhibitors of rat liver mitochondrial monoamine oxidase (MAO) A and B. The nature of the aromatic ring and the position of substituents in it were crucial for manifestation of the inhibitory activity. 3,4- and 2,4-Chlorobenzyloxycarbonyl-EDA derivatives were the most potent MAO A inhibitors. The inhibition of both MAO A and to a lesser extent MAO B depended on preincubation time with these inhibitors. The activity of both enzymes did not recover completely after repeated sedimentation and resuspension of inhibitor-treated mitochondria. The data suggest that these compounds exhibit properties of tight-binding reversible inhibitors of MAO A and B. The development of a new generation of MAO inhibitors causing simultaneous reversible nonselective inhibition of MAO A and B must meet one important criterion, the same type of inhibition of both the enzymes.

Animals↗
PubMed1999

Inhibitor analysis of angiotensin I-converting and kinin-degrading activities of bovine lung and testicular angiotensin-converting enzyme.

Inhibition of bovine lung and testicular angiotensin-converting enzyme (ACE) by some well-known ACE inhibitors (lisinopril, captopril, enalapril), new substances (Nalpha-carboxyalkyl dipeptides PP-09, PP-35, and PP-36), and phosphoramidon was investigated using Cbz-Phe-His-Leu and FA-Phe-Phe-Arg (C-terminal analogs of angiotensin I and bradykinin, respectively) as the substrates. The somatic (two domains) and testicular (single domain) isoenzymes demonstrated different kinetic parameters for hydrolysis of these substrates. All of the inhibitors were competitive inhibitors of both ACE isoforms, and the Ki values were substrate-independent. The relative potencies of the inhibitors for both enzymes were: lisinopril > captopril > PP-09 > enalapril > PP-36 > PP-35 > phosphoramidon. The inhibition efficiency of PP-09 was comparable with those of the well-known ACE inhibitors. Captopril was more effectively bound to the somatic ACE (Ki = 0.5 nM) than to the testicular isoform (Ki = 6.5 nM).

Angiotensin I↗
PubMed1998

N-alkyloxycarbonyl derivatives of ethylene diamine as monoamine oxidase inhibitors.

A series of urethane type derivatives of ethylene diamine (EDA) was synthesised and tested as inhibitors of monoamine oxidase (MAO) A and B. Nature of aromatic ring and a position of substituents in it were important for the inhibitory activity. Chlorobenzyloxycarbonyl-EDA derivatives exhibited selective inhibition of MAO-A with 3,4-Cl2-C6H4CH2OCO-EDA being a most potent and selective MAO-A inhibitor (IC50 4 microM). Within the compounds studied, 3,4-dichloro-benzyloxycarbonyl-EDA exhibited most potent inhibition of MAO-A. This compound inhibited the activity of rat liver MAO-A non-competitively with Ki (slope) value of 3.6 microM, whereas the inhibition of rat liver MAO-B was competitive with Ki (slope) value of 56 microM (not shown). 2.4-Dichlorobenzyloxycarbonyl-EDA also inhibited rat liver MAO-A in a non-competitive manner with Ki of 14.6 microM.

Animals↗
PubMed1997

Subcellular localization, substrate specificity and crystallization of duodenase, a potential activator of enteropeptidase.

Duodenase, a serine protease from bovine duodenum mucosa, was located in endoplasmic reticulum, the Golgi secretory granules of epithelial cells and ducts of Brunner's glands by the A-gold immunocytochemical method. Duodenase exhibits trypsin-like and chymotrypsin-like specificities with a preference for substrates having lysine at the P1 and proline at the P2 positions. The kinetic constants for the hydrolysis of 21 potential duodenase substrates are reported. The best substrates were found to be alpha-N-tosylglycylprolyllysine 4-nitroanilide (k[cat]/Km of 35000 M[-1] s[-1]), alpha-N-succinylthreonylprolyllysine 4-nitroanilide (k[cat]/Km of 18000 M[-1] s[-1]) and alpha-N-serylprolyllysine 4-nitroanilide (k[cat]/Km of 2600 m[-1] s[-1]), all of which contain the P1-P3 sequence of the enteropeptidase zymogen/activation site. On the basis of its catalytic properties and sites of localization, duodenase has been postulated to be an activator of the enteropeptidase precursor. A tetradecapeptide (LVTQEVSPKIVGGS) having the P9-P5'sequence of the cleavage site of zymogen activation of bovine proenteropeptidase was synthesized, and kinetic parameters of its hydrolysis by duodenase were determined (Km of 87 microM; k[cat] of 1.4 s[-1]; k[cat]/Km of 16000 M[-1] s[-1]). Crystals of duodenase frozen in a stream of liquid nitrogen diffracted synchrotron X-rays to 0.2-nm resolution.

Amino Acid Sequence↗
PubMed1995

Proteolytic enzymes at various stages of oncogenic transformation of rat fibroblasts. I. Aspartyl and cysteine proteinases.

Aspartyl and cysteine proteinases at distinct stages of carcinogenesis were analyzed in rat embryo fibroblasts, sequentially immortalized and transformed by 2 different genes: the early region of simian adenovirus SA7 and c-Ha-ras oncogene. The dynamics of expression and distribution of proteinases throughout the transformation process were examined. It was shown that in immortalized and transformed cells the activities of the aspartyl and cysteine proteinases were expressed to a variable degree and that the expression was dependent on cell-propagation time in vitro. The increase in activity both of cathepsin-D-like aspartyl proteinase and of cathepsin-L- and -B-like cysteine proteinases in cell lysates was correlated with the stages of fibroblast transformation (immortalization and tumorigenic transformation). In all cell types the major part of cysteine proteinases was localized inside the cell, while the cathepsin-D-like proteinase was apparently predominant among secreted proteinases. The cathepsin-L-like proteinase accounts for the major part of the cysteine-proteinase activity as measured by Z-Phe-Arg-MCA hydrolysis. We suggest that considerable portions of the cathepsin-D- and -L-like proteinases in all cell lines studied are secreted as a complex with inhibitor(s) and that inhibitor expression plays an important role in regulating the activity of cathepsin-D-like proteinase at different stages of transformation. Cathepsin-L-like proteinase is probably secreted in the precursor form.

Amino Acid Sequence↗
PubMed1994

Activation of carboxylic acids by pyrocarbonates. Synthesis of arylamides of N-protected amino acids and small peptides using dialkyl pyrocarbonates as condensing reagents.

Activation of carboxylic acids was achieved via dialkyl pyrocarbonates (ROCO)2O, (R = ethyl, isopropyl, sec-butyl, tert-butyl) in aprotic solvents in the presence of tertiary amines. A convenient one-pot procedure for the preparation of arylamides from N-protected amino acids including arginine and from di-tert-butyl pyrocarbonate in the presence of pyridine (Boc2O-pyridine system) was reported. Analogously, diisopropyl, di-sec-butyl or diethyl pyrocarbonate could be used in the presence of N-methylmorpholine or triethylamine. A wide variety of N-protected amino acid arylamides were prepared in good yields.

Amides↗
PubMed1994

[A new fluorogenic substrate of carboxypeptidase H--o-coumaroylphenylalanyl-alanyl-arginine].

New fluorogenic substrate of carboxypeptidase H, Cum-Phe-Ala-Arg-OH, is hydrolyzed by this enzyme to give Cum-Phe-Ala-OH, which is completely extracted by chloroform from the reaction mixture and whose fluorescence increases remarkably by the presence of triethylamine. When the hydrolysis of the novel substrate is compared with Dns-Phe-Ala-Arg-OH, the former has Km twice as low (30 microM) and kcat four times as high (5.8 s-1). Activation of the enzyme by Co2+ in reactions with the two substrates was also studied. The novel substrate is useful for the enzyme's assay in homogenates of various animal tissues.

Amino Acid Sequence↗
PubMed1993

[Proteolytic enzymes in human lymphocytic leukemia cells. II. Comparative characteristics of proteolytic enzymes and their inhibitors in three differing types of lymphoid cells].

A comparative study of proteolytic enzymes and their inhibitors in three human leukemic lymphoid cell populations has been carried out. The lysates of all lymphoid cells contained cathepsins D, B, L and H as well as serine trypsin-like proteinases, several aminopeptidases, dipeptidyl aminopeptidase IV and plasminogen activator (urokinase type). The activities of individual proteinases and their ratios in all cell types under study varied essentially, suggesting that lymphoid cells with different functions have different sets of proteolytic enzymes. FPLC chromatography of the lysates revealed the presence of inhibitors of cysteine and serine trypsin-like proteinases. The procedure for isolation of cathepsins D, B, L and H and of their inhibitors has been proposed and partially purified protein preparations obtained. Some properties of cathepsins B and L and those of their inhibitor have been examined.

Amino Acid Sequence↗
PubMed1992

[Determination of esterase activity of human and animal serine proteinases using fluorogenic esters of amino acids as substrates].

Two fluorogenic derivatives of amino acids are proposed as substrates for the purpose of enzymatic assay: N-benzyloxycarbonyl-phenylalanine-4-methyl umbelliferyl ester (substrate-1) and tert-butyloxycarbonyl-alanine-4-methyl-umbelliferyl ester (substrate-II). Chymotrypsin-like (hydrolysis of substrate-1), elastase-like (hydrolysis of substrate-II) esterase activity of bovine pancreatic chymotrypsin, activities of cathepsin G and elastase from human, porcine and rat neutrophils and esterase activity of human, porcine and rat serum were assayed. Differences in the level of chymotrypsin-like and elastase-like activities of human, porcine and rat serum were established. Activities of purified elastase and cathepsin G from human and animal neutrophils were shown to have no significant distinctions.

Animals↗
PubMed1992

Activation of carboxylic acids by pyrocarbonates. Synthesis of symmetric anhydrides and esters of N-protected amino acids using dialkyl pyrocarbonates as condensing reagents.

Activation of carboxylic acids was achieved via dialkyl pyrocarbonates (ROCO)2O, R = C2H5, i-C3H7, sec-C4H9, tert.-C4H9) in aprotic solvents in the presence tertiary amines. A convenient procedure for the preparation of carboxylic acid anhydrides from carboxylic acids and di-tert.-butyl pyrocarbonate in the presence of pyridine is reported. Analogously, di-isopropyl- or diethyl pyrocarbonate may be used in the presence of N-methylmorpholine (triethylamine). With pyridine, di-isopropyl- or diethyl pyrocarbonate carboxylic acids form isopropyl- or ethyl esters, respectively. A wide variety of esters were prepared in good yields in a one-pot procedure from carboxylic acids, including N-protected amino acids, and alcohols or from phenols by means of di-tert.-butyl pyrocarbonate in the presence of pyridine (Boc2O-pyridine system). t-Butyl esters of carboxylic acids were obtained by the same procedure with 4-dimethylaminopyridine. In the absence of carboxylic acid, with 4-dimethylaminopyridine Boc2O and alcohols generate alkyl tert.-butyl carbonates.

Amino Acids↗
PubMed1991

[Determination of the esterase activity of serine proteinases using synthetic substrates].

The authors suggest a highly sensitive rapid and simple method for measuring esterase activities of bovine pancreatic chymotrypsin, human neutrophilic cathepsin D, and elastase, and of human blood serum chymotrypsin-like esterase and elastase-like esterase activities, with fluorogenic synthetic ethers, amino acid derivatives, employed as substrates: N-benzoxycarbonylphenylalanine 4-methylumbelliferyl ester (Z-Phe-OMC) and tret-butyloxycarbonyl-1-alanine 4-methylumbelliferyl ester (BOC-Ala-OMC).

Animals↗
PubMed1991

[Enzymatic synthesis of acyl peptides containing p-nitroanilides of basic amino acids].

A method is suggested for synthesis of acylpeptides, containing arginine or lysine p-nitroanilides at the C-terminus, via the acyl transfer reaction catalyzed by the Bacillus subtilis serine proteinase. Acyl-di- and acyltripeptide ethers with L- and D-amino acids were used as the carboxyl component taken in a twofold excess. When the concentration of dimethylformamide increases, the hydrolysis of the initial ether and the reaction product diminishes. Because of the enzyme inactivation by dimethylformamide the latter's optimal concentration is 70-80%.

Acylation↗