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Biomedical subjects

J Brzin

Publications and source records attributed to J Brzin.

36 records · Page 2Linked to original sources
PubMed1986

Human cysteine proteinases and their protein inhibitors stefins, cystatins and kininogens.

The cathepsins B, H and L of human origin were isolated in pure form in sufficient quantities for structural characterization. The complete amino acid sequence of human liver cathepsin B was determined. Partial amino acid sequences of the human kidney cathepsin H and L show the highly conserved region around the active site cysteine. The cysteine proteinase inhibitors stefin A, human stefin B and human cystatin C were isolated, characterized and sequenced. Their amino acid sequences are compared with sequences of other protein inhibitors of the stefin and cystatin family, showing a high degree of homology throughout both families. The stefin and cystatin family, together with newly discovered kininogen family belong to the same superfamily of cystatins. The constructed dendrogram shows that the most closely related inhibitors so far sequenced are human stefin B and rat liver TPI.

Amino Acid Sequence↗
PubMed1986

Kininogens: inhibitors of cysteine proteinases in plasma and a similar inhibitor in chicken egg white.

Isolation, based on their inhibitory properties, is a fast and simple alternative method for the preparation of kininogens from human plasma. Pure native low Mr kininogen can be obtained in a much higher yield than with classical methods, provided that a similarly efficient inhibition of proteolysis is included. Chicken egg white also contains a high Mr inhibitor of cysteine proteinases. It closely resembles low Mr kininogen in its molecular weight, acidic isoelectric point and 1:2 inhibitor to enzyme molar binding ratio. Its relation to chicken serum kininogen is not known.

Animals↗
PubMed1985

Cystatin, a protein inhibitor of cysteine proteases alters viral protein cleavages in infected human cells.

Chicken cystatin is a previously described small protein which has the property of inhibiting cysteine active site proteases. The protein, when added to cultured human cells, alters the intracellular proteolytic processing of poliovirus proteins, and causes a reduction in virus yield. It is suggested that the cystatin is able to penetrate to the cellular cytoplasm and inhibit the action of the poliovirus protease.

Animals↗
PubMed1985

Human plasma kininogens are identical with alpha-cysteine proteinase inhibitors. Evidence from immunological, enzymological and sequence data.

Human high- and low-Mr kininogens were shown to be potent inhibitors of cysteine proteinases such as cathepsin L and papain (Ki = 17-48 pM). A strong immunological cross-reaction between the kininogens and low-Mr alpha-cysteine proteinase inhibitor from human plasma was found. Comparison of partial amino acid sequences from high- and low-Mr kininogen and low-Mr alpha-cysteine proteinase inhibitor demonstrated sequence identity for all segments analyzed. These findings suggest that the kininogens and the alpha-cysteine proteinase inhibitors from human plasma are identical proteins.

Amino Acid Sequence↗
PubMed1985

Crystallization of chicken egg white cystatin, a low molecular weight protein inhibitor of cysteine proteinases, and preliminary X-ray diffraction data.

The shorter-chain form of chicken egg white cystatin has been crystallized in 1.6 M-phosphate buffer at pH 4.0 by vapour diffusion. The crystals are of trigonal space group P3121 (or P3221), have cell constants a = b = 47.9 A, c = 87.5 A, alpha = beta = 90 degrees, gamma = 120 degrees, and contain one molecule of 12,191 molecular weight per asymmetric unit. They diffract well to about 2.0 A resolution and are suitable for X-ray crystal structure analysis.

Animals↗
PubMed1984

Human cystatin, a new protein inhibitor of cysteine proteinases.

A new low-molecular weight protein inhibitor of cysteine proteinases, human cystatin, was isolated from sera of patients with autoimmune diseases. It inhibits papain, human cathepsin H and cathepsin B. According to its partially determined amino-acid sequence, human cystatin is highly homologous to egg white cystatin, but only distantly related to stefin, the cytosolic protein inhibitor of cysteine proteinases isolated from human polymorphonuclear granulocytes. Very probably human cystatin is identical with human gamma-trace, a microprotein of known sequence but hitherto unknown function.

Amino Acid Sequence↗
PubMed1983

Protein inhibitors of cysteine proteinases. I. Isolation and characterization of stefin, a cytosolic protein inhibitor of cysteine proteinases from human polymorphonuclear granulocytes.

A protein inhibitor of cysteine proteinases, "stefin", was purified from cytosol of human polymorphonuclear granulocytes. Affinity chromatography on carboxymethylated papain-Sepharose was used as the first step, followed by ion exchange chromatography on DEAE-Sephacel, which resolved four inhibitory peaks. The main peak, comprising approx. 80% of total inhibitory activity was characterized. It was found to be a homogenous protein with an apparent molecular mass slightly lower than that of cytochrome c and with an isoelectric point of 4.65. The inhibitor inhibits papain at a molar ratio of 1:1 as well as cathepsin B and H, but it does not inhibit serine and aspartic proteinases. It is stable at elevated temperature and in alkaline pH, but looses its activity in acid pH. Oxidized glutathione has no effect on its inhibitory activity.

Chromatography, Affinity↗
PubMed1983

Protein inhibitors of cysteine proteinases. II. Primary structure of stefin, a cytosolic protein inhibitor of cysteine proteinases from human polymorphonuclear granulocytes.

The primary structure of stefin, a new cysteine proteinase inhibitor from the cytosol of human polymorphonuclear granulocytes, was determined by amino-acid sequence analysis. The protein consists of 98 amino-acid residues and contains no cysteine. Its molecular mass was calculated to be 11006 Da. The sequence was obtained by automatic solid-phase Edman degradation of the uncleaved protein and its cyanogen bromide fragments. There is no striking evidence for a sequence homology with known families of protein inhibitors of proteinases.

Amino Acid Sequence↗
PubMed1983

Protein inhibitors of cysteine proteinases. III. Amino-acid sequence of cystatin from chicken egg white.

Cystatin, the protein inhibitor of cysteine proteinases from chicken egg white was purified by a new method. The two major forms with pI 6.5 (Peak I) and 5.6 (Peak II) were separated. Molecular masses of both forms are approx. 12700 Da as determined by gel chromatography; Form A from Peak I has a molecular mass of 12191 Da as calculated from its amino-acid sequence. The complete amino-acid sequence of Form A was determined by automated solid-phase Edman degradation of the whole inhibitor and its cyanogen bromide fragments. It contains 108 amino-acid residues. Form B from Peak II represents an elongation of Form A by 8 amino-acid residues at the N-terminus. Cystatin contains four cysteine residues, presumably forming two disulphide bridges. Comparison of the amino-acid sequences and near ultraviolet circular dichroism spectra of stefin, the cysteine proteinase inhibitor from human granulocytes, and cystatin shows that the two proteins are entirely different. According to the primary structures, probably neither proteinase inhibitor is involved in a thiol-disulphide exchange mechanism in the interaction with its target enzyme.

Amino Acid Sequence↗
PubMed1982

Biochemical and biological characteristics of leucocyte proteinase inhibitors.

Pig leucocytes contain inhibitors of neutral and thiol proteinases. These proteins could be isolated from post-granule supernatant fraction as well as from nuclear extract using ion exchange chromatography, gel chromatography and affinity chromatography. Inhibitors differ in molecular weight, isoelectric point, immunologically and their inhibition ability against tested enzymes.

Animals↗
PubMed1982

Some further characteristics of endogenous proteinase inhibitors.

Leucocytes and spleen contain four different types of protein proteinase inhibitors. Two of them can be inactivated by cathepsin D. In this work biochemical and immunological studies of the inactivation of I-2 by cathepsin D are presented. Polyacrylamide gel electrophoretic examinations indicate that cathepsin D inactivates I-2 by hydrolysis of the inhibitor molecule. The conversion of the active inhibitor into inactive protein proceeds catalytically. The studies on the inhibitor mechanism of the isoinhibitors of I-1 type explain the unusual inhibitor property of this type of inhibitor to inhibit two different types of proteinases, cysteine and serine. The evidence suggests that the inhibitory mechanism is based on an active sulfhydryl group of the inhibitor which may interact with the disulfide bridge of the inhibited proteinase.

Animals↗
PubMed1981

Inhibitory mechanism of sericystatin, an intracellular proteinase inhibitor, reacting with cysteine proteinases.

Studies are reported on the inhibitory mechanism of an endogenous inhibitor, which has the ability of inhibiting both cysteine and serine proteinases. On the basis of this unusual inhibitory property, we propose the name "sericystatin". The cysteine proteinases (cathepsin B and papain) can be reactivated from their complex with sericystatin by the action of oxidized glutathione or by chymotrypsin-like neutral proteinases. The inhibitory activity of sericystatin can be inactivated by treatment with oxidized glutathione. The results indicate that sericystatin inhibits these enzymes by a reversible thiol-disulphide exchange mechanism.

Animals↗
PubMed1977

Isolation and characterization of inhibitors of neutral proteinases from spleen.

Two different types of neutral proteinase inhibitors were isolated from postmicrosomal supernatant of bovine spleen. Inhibitor A with molecular weight 40,000 inhibits elastases and chymotrypsin-like neutral proteinases from bovine spleen, whereas inhibitor B with estimated molecular weight 20 000 inhibits only chymotrypsin-like neutral proteinase.

Animals↗