Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Complement factor D, a complement system serine protease, circulating in vivo as its active form, accumulates in patients with chronic renal failure. The pathophysiological role of this active protease in these patients was examined by studies on activities of excess factor D on 10 synthetic peptide substrates for some usual serine proteases. The most sensitive of these substrates to factor D was Boc-Gln-Ala-Arg-MCA, which is used as a substrate for trypsin. The proteolytic activity of factor D (2.17 unit/mg/h) on this substrate was estimated to be 10(-5)-fold that of trypsin (2.18 x 10(5) unit/mg/h). The activities of factor D on other synthetic substrates were lower. Thus the proteolytic activity of factor D is considered to be very specific for its natural substrate, complement factor B bound with C3b, even when it is highly accumulated in vivo. The inhibitory effects of some serine protease inhibitors used clinically (nafamostat mesilate, sepinostat mesilate, camostat mesilate and gabexate mesilate) on the proteolytic activity of factor D on its natural substrate, factor B, were also investigated. Of these synthetic compounds, nafamostat mesilate was the most effective inhibitor (ID50:25 microM) of the activity of factor D on factor B.
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PMID:Evaluation of the proteolytic activity of factor D accumulated as an active serine protease in patients with chronic renal failure. 819 Jan 80

A Limulus intracellular coagulation inhibitor, designated LICI, was isolated from hemocytes of the Japanese horseshoe crab (Tachypleus tridentatus), using three steps of chromatography, including dextran sulfate-Sepharose CL-6B, Sephacryl S-200, and Mono S. LICI is a single-chain glycoprotein with an apparent M(r) = 48,000 estimated by SDS-polyacrylamide gel electrophoresis. It blocks the amidolytic activities of Limulus lipopolysaccharide-sensitive serine protease, factor C, by forming a covalent 1:1 complex with the protease. The second-order rate constant for inhibition of factor C was 2.5 x 10(6) M-1 s-1 at 37 degrees C. LICI also inhibited human alpha-thrombin, rat salivary kallikrein, bovine plasmin, and trypsin but not Limulus clotting enzyme, Limulus factor B, bovine factor Xa, human factor XIa, human tissue plasminogen activator, human urokinase, chymotrypsin, elastase, and papain. Glycosaminoglycans such as heparin and heparan sulfate had no effect on the inhibitory activity. A cDNA coding for LICI was isolated from a hemocyte cDNA library. The open reading frame of the 1,257-base pair cDNA codes for the mature protein of 394 amino acids, of which 223 residues were confirmed by amino acid sequence analysis. LICI shows significant sequence identities to members of the serpin superfamily, such as human plasminogen activator inhibitor type 2 (40%) and human monocyte/neutrophil elastase inhibitor (39%). LICI contains a putative reactive site, -Arg-Ser-, at the corresponding position present in several inhibitors of the serpin superfamily. The subcellular localization, determined using an anti-LICI polyclonal antibody, indicated that LICI colocates with the Limulus serine protease zymogens in large granules in the hemocyte.
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PMID:A Limulus intracellular coagulation inhibitor with characteristics of the serpin superfamily. Purification, characterization, and cDNA cloning. 827 48

We tested the hypothesis of anaphylaxis as a pathogenic factor in acute myocardial infarction. Mast cells were counted in the myocardium, coronary arteries and airways. Total serum IgE, mast cell tryptase, complements C3, C4, and factor B, were measured in 29 cases of sudden death from coronary artery thrombosis and in 27 controls. We found increased numbers of mast cells in the coronary arteries following coronary death: 46 +/- 21 (SD) compared with 22 +/- 10 (SD) in the control group (P < 0.002). In the myocardium and airways there were no differences between the groups. The concentrations of tryptase and IgE in serum did not differ between the groups although 20% of the coronary deaths had elevated values (> 200 kU/l) compared with 8% in the control group. Of the complement factors, C3 was higher in the coronary deaths (P < 0.05) than in the controls. The results give no evidence of anaphylactic reaction in the pathogenesis of acute myocardial infarction.
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PMID:Immunoglobulin E, mast cell-specific tryptase and the complement system in sudden death from coronary artery thrombosis. 870 40

In 7 patients who received liver transplants, 12 plasma proteins were subjected to phenotype analysis in donor and recipient before and after transplantation. The plasma proteins analyzed were haptoglobin, transferrin, glycoprotein GC, alpha-1-antitrypsin, complement factor 3 (C3), orosomucoid 1, properdin factor B, complement factor 6, alpha-2-HS-glycoprotein (A2HS), plasminogen, factor B of coagulation factor XIII, and interalpha-trypsin-inhibitor (ITI). Classification was done with isoelectric focusing or agarose gel electrophoresis (C3). A change from recipient to donor type was observed for all systems with the exception of C3. This is the first time such data have been obtained for the A2HS and ITI systems. The time is indicated at which the recipient type disappeared and the donor type appeared. In addition to the expected phenotype changes from recipient to donor type, unexpected results were found in some systems. For instance, in 2 patients a mixed type was synthesized, or new phenotypes appeared. Possible explanations include blood transfusions, immunosuppressive therapy, extrahepatic sites of synthesis and disturbed transplant function. The usefulness of phenotype determination as a diagnostic criterion for transplant function is discussed.
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PMID:Phenotype change in polymorphic plasma proteins following liver transplantation. 906 99

Factor B and C2 are serine proteases that carry the catalytic sites of the complement C3 and C5 convertases. Their protease domains are activated by conformational changes that occur during convertase assembly and are deactivated upon convertase dissociation. Factor B and C2 share an 8-amino acid conserved sequence near their serine protease termini that is not seen in other serine proteases. To determine its importance, 24 factor B mutants were generated, each with a single amino acid substitution in this region. Whereas most mutants were functionally neutral, all five different substitutions of aspartic acid 715 and one phenylalanine 716 substitution severely reduced hemolytic activity. Several aspartic acid 715 mutants permitted the steps of convertase assembly including C3b-dependent factor D-mediated cleavage and activation of the high affinity C3b-binding site, but the resulting complexes did not cleave C3. Given that factor B and C2 share the same biological substrates and that part of the trypsin-like substrate specificity region is not apparent in either protein, we propose that the conserved region plays a critical role in the conformational regulation of the catalytic site and could offer a highly specific target for the therapeutic inhibition of complement.
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PMID:A conserved element in the serine protease domain of complement factor B. 974 77

Factor D is a serine protease essential for the activation of the alternative pathway of complement. The structures of native factor D and a complex formed with isatoic anhydride inhibitor were determined at resolution of 2.3 and 1.5 A, respectively, in an isomorphous monoclinic crystal form containing one molecule per asymmetric unit. The native structure was compared with structures determined previously in a triclinic cell containing two molecules with different active site conformations. The current structure shows greater similarity with molecule B in the triclinic cell, suggesting that this may be the dominant factor D conformation in solution. The major conformational differences with molecule A in the triclinic cell are located in four regions, three of which are close to the active site and include some of the residues shown to be critical for factor D catalytic activity. The conformational flexibility associated with these regions is proposed to provide a structural basis for the previously proposed substrate-induced reversible conformational changes in factor D. The high-resolution structure of the factor D/isatoic anhydride complex reveals the binding mode of the mechanism-based inhibitor. The higher specificity towards factor D over trypsin and thrombin is based on hydrophobic interactions between the inhibitor benzyl ring and the aliphatic side-chain of Arg218 that is salt bridged with Asp189 at the bottom of the primary specificity (S1) pocket. Comparison of factor D structural variants with other serine protease structures revealed the presence of a unique "self-inhibitory loop". This loop (214-218) dictates the resting-state conformation of factor D by (1) preventing His57 from adopting active tautomer conformation, (2) preventing the P1 to P3 residues of the substrate from forming anti-parallel beta-sheets with the non-specific substrate binding loop, and (3) blocking the accessibility of Asp189 to the positive1y charged P1 residue of the substrate. The conformational switch from resting-state to active-state can only be induced by the single macromolecular substrate, C3b-bound factor B. This self-inhibitory mechanism is highly correlated with the unique functional properties of factor D, which include high specificity toward factor B, low esterolytic activity toward synthetic substrates, and absence of regulation by zymogen and serpin-like or other natural inhibitors in blood.
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PMID:Structures of native and complexed complement factor D: implications of the atypical His57 conformation and self-inhibitory loop in the regulation of specific serine protease activity. 975 54

The interaction between complement component factor B and the triazine dye ligand Cibacron Blue F3G-A coupled to a cross-linked agarose matrix (Blue Sepharose) was found to involve the Bb part of the molecule, and to be inhibited by benzamidine. Human, chicken and rainbow trout factor B which had bound to Blue Sepharose could, subsequently be eluted with benzamidine. Other serine proteases (C2, factor II, factor IX, trypsin, chymotrypsin, proteinase 3) also bound to Blue Sepharose but only those belonging to the trypsin family could be eluted with benzamidine. Trypsin treated with the active-site inhibitor phenylmethylsulfonyl fluoride did not bind to Blue Sepharose and pretreatment of Blue Sepharose with benzamidine did not influence binding of proteases. We conclude that trypsin-like serine proteases can be purified on Blue Sepharose and that the interaction of these serine proteases with Blue Sepharose involves the active site of the enzyme.
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PMID:Affinity chromatography of serine proteases on the triazine dye ligand Cibacron Blue F3G-A. 983 58

Factor B is a serine protease, which despite its trypsin-like specificity has Asn instead of the typical Asp at the bottom of the S(1) pocket (position 189, chymotrypsinogen numbering). Asp residues are present at positions 187 and 226 and either one could conceivably provide the negative charge for binding the P(1)-Arg of the substrate. Determination of the crystal structure of the factor B serine protease domain has revealed that the side chain of Asp(226) is within the S(1) pocket, whereas Asp(187) is located outside the pocket. To investigate the possible role of these atypical structural features in substrate binding and catalysis, we constructed a panel of mutants of these residues. Replacement of Asp(187) caused moderate (50-60%) decrease in hemolytic activity, compared with wild type factor B, whereas replacement of Asn(189) resulted in more profound reductions (71-95%). Substitutions at these two positions did not significantly affect assembly of the alternative pathway C3 convertase. In contrast, elimination of the negative charge from Asp(226) completely abrogated hemolytic activity and also affected formation of the C3 convertase. Kinetic analyses of the hydrolysis of a P(1)-Arg containing thioester by selected mutants confirmed that residue Asp(226) is a primary structural determinant for P(1)-Arg binding and catalysis.
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PMID:Mutational analysis of the primary substrate specificity pocket of complement factor B. Asp(226) is a major structural determinant for p(1)-Arg binding. 1061 28

In the previous study, the proteomes of the human hepatoma cell line BEL-7404 and the normal human liver cell line L-02 were separated by high resolution two-dimensional electrophoresis (2-DE). Image analysis revealed that 99 protein spots showed quantitative and qualitative variations that were significant (P < 0.01) and reproducible. Here we report the identification results of some of these protein spots. Protein spots excised from 2-D gels were subjected to in-gel digestion with trypsin, and the resulting peptides were measured by microbore high performance liquid chromatography - ion trap - mass spectrometry (LC-IT-MS) to obtain the tandem mass (MS/MS) spectra. Twelve protein spots were identified with high confidence using SEQUEST with uninterpreted MS/MS raw data. Besides inosine-5'-monophosphate dehydrogenase 2, heat shock 27 kDa protein, calreticulin and calmodulin, whose expression was elevated in hepatoma cells, glutathione-S-transferase P was identified from hepatoma cells in which its level was 18-fold higher compared to human liver cells. Two spots were identified as the homologs of reticulocalbin for the first time in hepatoma cells and their expression increased compared to liver cells. However, tubulin beta-1 chain and natural killer cell enhancing factor B were downregulated in hepatoma cells. A tumor suppressing serpin, maspin precursor, was identified from one spot whose quantity was much higher in the normal liver cell line. More interestingly, epidermal fatty acid-binding protein (E-FABP) and fatty acid-binding protein, adipocyte-type (A-FABP), were detected in liver cells but not in hepatoma cells. The functional implication of the identified proteins was discussed.
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PMID:Identification of differentially expressed proteins between human hepatoma and normal liver cell lines by two-dimensional electrophoresis and liquid chromatography-ion trap mass spectrometry. 1100 23

The complement fragment-3a (C3a) acts via a G protein-coupled C3aR and is of importance in allergic and inflammatory diseases. Recent studies suggest the presence of complement proteins in the epidermal compartment and synthesis of some of these proteins (C3, factor B, and factor H) by human primary keratinocytes (KCs) during inflammation. However, expression of C3aR and its role in human KCs is not elucidated thus far. In this study, we demonstrate the expression of C3aR on KCs as detected by quantitative real-time RT-PCR and flow cytometry. IFN-gamma and IFN-alpha strongly up-regulated the surface expression of C3aR on KCs among all other cytokines tested. After up-regulation of C3aR by IFN-gamma and IFN-alpha, we observed the induction of five genes (CCL2, CCL5, CXCL8, CXCL10, and C3) after stimulation of KCs with C3a in microarray analysis. We confirmed the induction of C3 and CCL2 at RNA and protein levels. Furthermore, incubation of C3 with skin mast cells tryptase resulted in the generation of C3 fragments with C3a activity. In conclusion, our data illustrate that epidermal KCs express functional C3aR. The increases of C3 and CCL2 synthesis by C3a and C3 activation by skin mast cell tryptase delineates a novel amplification loop of complement activation and inflammatory responses that may influence the pathogenesis of allergic/inflammatory skin diseases.
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PMID:Induction of C3 and CCL2 by C3a in keratinocytes: a novel autocrine amplification loop of inflammatory skin reactions. 1698 79


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