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B Lenarcic

Publications and source records attributed to B Lenarcic.

35 records · Page 2Linked to original sources
PubMed1993

Participation of cathepsin L on bone resorption.

The proteinase responsible for bone collagen degradation in osteo-resorption was examined. The bone pit formation induced by parathyroid hormone (PTH) was markedly suppressed by leupeptin, E-64 and cystatin A, while no inhibition was observed by CA-074, a specific inhibitor of cathepsin B. Pig leucocyte cysteine proteinase inhibitor (PLCPI), a specific inhibitor of cathepsin L, and chymostatin, a selective inhibitor of cathepsin L, completely inhibited the pit formation. Cathepsin L activity in osteoclasts was much higher than the other cathepsin activities. Serum calcium in rats placed on a low calcium diet was decreased by treatment of E-64 or cystatin A, but not by CA-074. These findings suggest that cathepsin L is the main proteinase responsible for bone collagen degradation.

Animals↗
PubMed1992

Characterization and structure of pineapple stem inhibitor of cysteine proteinases.

The complete amino acid sequence of the inhibitor of cysteine proteinases from pineapple stem acetone powder was determined. The inhibitor consists of 52 amino acids and is composed of two polypeptide chains (41 and 11 amino acids) linked via disulphide bonds. It differs from already known sequences in one to four amino acids. Data from its amino acid sequence analysis clearly show that this inhibitor cannot be a member of the cystatin superfamily. The Ki values for papain, bromelain and cathepsin L were determined.

Amino Acid Sequence↗
PubMed1991

Folding studies of the cysteine proteinase inhibitor--human stefin A.

Reversible GuHCl denaturation of human stefin A (25 degrees C, pH 8) was monitored by the tyrosine fluorescence, by circular dichroism in the near UV and by circular dichroism in the far UV. In each case a midpoint of 2.8 +/- 0.1 M GuHCl was obtained, demonstrating the cooperativity of the denaturation. Kinetics of the slow folding on diluting the protein from the GuHCl denatured state, was also measured by the three spectroscopic probes (10 degrees C, pH 8). Results conform to a sequential mechanism. Denaturant concentration and temperature dependence of the slow folding were measured by fluorescence. From a linear Arrhenius plot the Ea of 100 +/- 5 kJ/mol was read. 'Double mixing' experiments revealed a slow reaction going on in the unfolded state which influenced the amplitude of the fluorescence changes. 'Double mixing' experiments performed by FPLC have shown that the folding itself, i.e., the formation of a compact state, was not dependent on the time spent under unfolding conditions.

Chromatography, High Pressure Liquid↗
PubMed1991

Inactivation of human cystatin C and kininogen by human cathepsin D.

A papain inhibitor of 22 kDa was isolated from human placenta and shown to be identical to residues Cys246-Leu373 of the third domain of human kininogen. This kininogen domain and recombinant human cystatin C were inactivated by peptide bond cleavages at hydrophobic amino acid residues due to the action of cathepsin D. These results further support the proposed role of cathepsin D in the regulation of cysteine proteinase activity.

Amino Acid Sequence↗
PubMed1990

The refined 2.4 A X-ray crystal structure of recombinant human stefin B in complex with the cysteine proteinase papain: a novel type of proteinase inhibitor interaction.

A stoichiometric complex of human stefin B and carboxymethylated papain has been crystallized in a trigonal crystal form. Data to 2.37 A resolution were collected using the area detector diffractometer FAST. The crystal structure of the complex has been solved by Patterson search techniques using papain as search model. Starting from the structure of chicken cystatin, the stefin structure was elucidated through cycles of model building and crystallographic refinement. The current crystallographic R factor is 0.19. Like cystatin, the stefin molecule consists of a five stranded beta-sheet wrapped around a five turn alpha-helix, but with an additional carboxy terminal strand running along the convex side of the sheet. Topological equivalence of stefin and cystatin reveal the previous sequence alignment to be incorrect in part, through deletion of the intermediate helix. The conserved residues form a tripartite wedge, which slots into the papain active site as proposed through consideration of the tertiary structures of the individual components (Bode et al., 1988). The main interactions are provided by the amino terminal 'trunk' (occupying the 'unprimed' subsites of the enzyme), and by the first hairpin loop, containing the highly conserved QVVAG sequence, with minor contributions from the second hairpin loop. The carboxyl terminus of stefin provides an additional interaction region with respect to cystatin. The interaction is dominated by hydrophobic contacts. Inhibition by the cysteine proteinase inhibitors is fundamentally different to that observed for the serine proteinase inhibitors.

Amino Acid Sequence↗
PubMed1990

Refolding of chicken cystatin and human stefin A studied by fast protein liquid chromatography (FPLC).

Denaturant gradient gel-chromatography [Endo, S. et al. (1983) Anal. Biochem. 131, 108-120] has been used to follow renaturation of chicken cystatin and human stefin A. Slow gradient of GuHCl was applied to the size-exclusion Superose 12 column. The column was maintained at 5 degrees C by circulating water from a cryostate. When the denatured protein has been injected it started to refold on the column. By the simplified equation, according to [Hanai, R. et al. (1986) Biophys. Chem. 25, 27-36] approximate kinetics of folding was obtained. No intermediate species in folding could be detected from 6M to 2M GuHCl, only the close-to-denatured state and the close-to-native state.

Animals↗
PubMed1990

Mutations in the QVVAG region of the cysteine proteinase inhibitor stefin B.

Variants of human stefin B were constructed by cassette mutagenesis. Val47 as the constituent of highly conserved QVVAG sequence was substituted by hydrophobic amino acids of increasing size - Ala, Ile and Phe. Recombinant proteins were expressed in E. coli and Ki values for papain were determined. Substitutions did not cause a major change in Ki value and we conclude that the interaction with the proteinases is not the reason for the conservation of the pentapeptide.

Base Sequence↗
PubMed1988

Cloning a synthetic gene for human stefin B and its expression in E. coli.

A gene coding for human stefin B was synthesized by the solid-phase phosphite method and cloned in the pUC8 cloning vector. The insert with the verified DNA sequence was subcloned into two expression vectors and expressed in E. coli as a fusion protein with beta-galactosidase and as a native protein. The CNBr cleaved fusion protein and the native recombinant stefin B were inhibitory to papain and reacted with antibodies against human stefin B.

Amino Acid Sequence↗
PubMed1988

Cathepsin D inactivates cysteine proteinase inhibitors, cystatins.

The formation of inactive complexes in excess molar amounts of human cathepsins H and L with their protein inhibitors human stefin A, human stefin B and chicken cystatin at pH 5.6 has been shown by measurement of enzyme activity coupled with reverse-phase HPLC not to involve covalent cleavage of the inhibitors. Inhibition must be the direct result of binding. On the contrary the interaction of cystatins with aspartic proteinase cathepsin D at pH 3.5 for 60 min followed by HPLC resulted in their inactivation accompanied by peptide bond cleavage at several sites, preferentially those involving hydrophobic amino acid residues. The released peptides do not inhibit papain and cathepsin L. These results explain reported elevated levels of cysteine proteinases and lead to the proposal that cathepsin D exerts an important function, through inactivation of cystatins, in the increased activities of cysteine proteinases in human diseases including muscular distrophy.

Amino Acid Sequence↗
PubMed1988

Chemical synthesis of a gene for human stefin A and its expression in E. coli.

A DNA containing the coding sequence for the human cysteine proteinase inhibitor stefin A was obtained by enzymic ligation of chemically synthesized deoxyoligonucleotides, using the Khorana ligation method. The 306-bp synthetic gene carries signals for the initiation and termination of its translation. The gene was expressed in E. coli using a cytoplasmic expression vector and stefin A was secreted under the control of the E. coli alkaline phosphatase signal sequence, respectively. The secreted hybrid protein was shown to exhibit biological properties similar to the native protein isolated from human plasma.

Amino Acid Sequence↗
PubMed1988

Interactions between a viral protease and cystatins.

The interactions of two cystatins with a viral cysteine protease were studied using several types of assays. Complex formation between the protease and inhibitor was directly demonstrated using a gel retardation assay. It was also shown that the formation of enzyme inhibitor complexes could occur after first binding either the enzyme or the inhibitor to filter paper, and ultimately decorating the complex with antibody and radio-labelled protein A or by preparing one of the protein ligands with an internal radiolabel. The procedure can be adapted to provide a method for screening expression libraries for protease or inhibitor genes. The inhibition of a cysteine protease by a cystatin was shown not to directly involve binding to the active site thiol of the enzyme, but rather to be the result of a steric block in the active site region which prevents large affinity labels and protein substrates from reaching the active site.

Animals↗
PubMed1988

A new purification procedure of human kidney cathepsin H, its properties and kinetic data.

A purification procedure of cathepsin H from human kidney is presented. It includes gel filtration, ion exchange chromatography, and covalent chromatography on thiol Sepharose as an essential step. Purified cathepsin H emerges in an isoelectric focusing gel at pH 6.1 and 6.3. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate shows a molecular mass of about 28 kDa. Less than 20% of the enzyme preparation can be separated into a heavy (24 kDa) and a light chain (4 kDa) after reduction and gel filtration on Sephacryl S-200. The partial amino-acid sequence of human cathepsin H shows its close similarity to rat cathepsin H. Inhibition constants (Ki) of cathepsins H and B with chicken cystatin, two forms of human stefin A, human stefin B, and two forms of human cystatin C are in the range of 10(-9) to 10(-11)M.

Amino Acid Sequence↗
PubMed1988

Structural and immunological relationship between laminin and the cysteine proteinase inhibitor stefin.

A sequence analogy was found between the C-terminal region of the B1 chain of laminin (residues 1538-1639) and cysteine proteinase inhibitors, in particular the stefin group. The sequence analogous with cysteine proteinase inhibitors occurs in fragment E8 obtained by elastase digestion of laminin. Antibodies raised against E 8 reacted with stefin but not with kininogen or cystatin.

Amino Acid Sequence↗
PubMed1988

Human cathepsin B and cysteine proteinase inhibitors (CPIs) in inflammatory and metabolic joint diseases.

Synovial fluid of patients with different inflammatory and metabolic joint diseases contains low-molecular CPIs (stefins and cystatins) and high-molecular CPIs (kininogens). An additional inhibitory fragment with a molecular mass of about 20 kDa, which is a part of the kininogen molecule, has been detected. Cathepsin B and cystatin C were determined by ELISA test in 47 patients with rheumatoid arthritis, seronegative spondylarthritis, osteoarthritis, undifferentiated arthritis and gout. A significantly higher amount of cathepsin B was found in patients with rheumatoid arthritis. The elevation of cathepsin B was accompanied by an increased amount of cystatin C.

Amino Acid Sequence↗
PubMed1986

Viral therapy: prospects for protease inhibitors.

Antiviral activities of known protease inhibitors were assayed in virus-infected cell cultures. Some members of the cystatin superfamily, in particular chicken cystatin, were able to block virus replication. In a binding assay, using purified components, chicken and human cystatin were able to bind poliovirus protease with affinities which were reflected in their relative antiviral potencies. Prospects for application of protease inhibitors in clinical viral infections are discussed.

Animals↗
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↗