Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protein C is a vitamin K-dependent protein, which exists in bovine plasma as a precursor of a serine protease. In this study, protein C was isolated to homogeneity from human plasma by barium citrate adsorption and elution, ammonium sulfate fractionation, DEAE-Sephadex chromatography, dextran sulfate agarose chromatography, and preparative polyacrylamide gel electrophoresis. Human protein C (M(r) = 62,000) contains 23% carbohydrate and is composed of a light chain (M(r) = 21,000) and a heavy chain (M(r) = 41,000) held together by a disulfide bond(s). The light chain has an amino-terminal sequence of Ala-Asn-Ser-Phe-Leu- and the heavy chain has an aminoterminal sequence of Asp-Pro-Glu-Asp-Gln. The residues that are identical to bovine protein C are underlined. Incubation of human protein C with human alpha-thrombin at an enzyme to substrate weight ratio of 1:50 resulted in the formation of activated protein C, an enzyme with serine amidase activity. In the activation reaction, the apparent molecular weight of the heavy chain decreased from 41,000 to 40,000 as determined by gel electrophoresis in the presence of sodium dodecyl sulfate. No apparent change in the molecular weight of the light chain was observed in the activation process. The heavy chain of human activated protein C also contains the active-site serine residue as evidenced by its ability to react with radiolabeled diisopropyl fluorophosphate. Human activated protein C markedly prolongs the kaolin-cephalin clotting time of human plasma, but not that of bovine plasma. The amidolytic and anticoagulant activities of human activated protein C were completely obviated by prior incubation of the enzyme with diisopropyl fluorophosphate. These results indicate that human protein C, like its bovine counterpart, exists in plasma as a zymogen and is converted to a serine protease by limited proteolysis with attendant anticoagulant activity.
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PMID:Human plasma protein C: isolation, characterization, and mechanism of activation by alpha-thrombin. 46 91

A low molecular weight protein protease inhibitor was purified from Japanese horseshoe crab (Tachypleus tridentatus) hemocytes. It consisted of a single polypeptide with a total of 61 amino acid residues. This protease inhibitor inhibited stoichiometrically the amidase activity of trypsin (Ki = 4.60 X 10(-10) M), and also had inhibitory effects on alpha-chymotrypsin (Ki = 5.54 X 10(-9) M), elastase (Ki = 7.20 X 10(-8) M), plasmin, and plasma kallikrein. However, it had no effect on T. tridentatus clotting enzyme and factor C, mammalian blood coagulation factors (activated protein C, factor Xa and alpha-thrombin), papain, and thermolysin. The complete amino acid sequence of this inhibitor was determined and its sequence was compared with those of bovine pancreatic trypsin inhibitor (BPTI) and other Kunitz-type inhibitors. It was found that the amino acid sequence of this inhibitor has a high homology of 47 and 43% with those of sea anemone inhibitor 5-II and BPTI, respectively. Thus, this protease inhibitor appeared to be one of the typical Kunitz-type protease inhibitors.
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PMID:Purification and amino acid sequence of Kunitz-type protease inhibitor found in the hemocytes of horseshoe crab (Tachypleus tridentatus). 330 64

The kinetic properties of the stimulation by Tl+ of the amidase activity of bovine plasma activated protein C (APC) and a limited-proteolytic derivative of this enzyme, des-1-41-light chain APC (GDAPC), which has no remaining gamma-carboxyglutamic acid residues, have been compared, along with a 205Tl+ NMR analysis of the interaction of this cation with these enzymes, at 6 degrees C. In contrast to other monovalent cations, the productive kinetic complex of Tl+ and APC involves only a single Tl+ site, or class of sites, and is similar to GDAPC in this regard. In the case of each enzyme, the kinetic mechanism that best describes the participation of Tl+ is a rapid equilibrium type with random addition of the cation and substrate to the enzyme. The dissociation constants of the Tl+ X APC and Tl+ X GDAPC complexes have been determined by NMR analysis and have been found to be very similar to the same constants as calculated by kinetic means. These cation sites are also present intact on each zymogen, demonstrating that they are not generated as a result of activation. Our results also show that the Ca2+ binding sites of these proteins are exclusive of the T1+ site and that some interference with Tl+ binding is exercised by an active site-directed affinity label. We conclude that Tl+ can be effectively employed as a spectroscopic probe of the monovalent cation sites that serve an extensive stimulatory role in the amidolytic and esterolytic activities of APC.
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PMID:205Tl+ as a spectroscopic probe of the monovalent cation binding sites of bovine plasma activated protein C and des-1-41-light-chain-activated protein C. 358 7

This report documents attempts to mimic the rate enhancement effect of thrombomodulin on human alpha-thrombin-catalyzed activation of human protein C in the absence of exogenous calcium. Specifically the following tryptamine analogs at 1 mM concentration were shown to enhance the protein C activation rate relative to a control with no added effector at pH 8.3 (50 mM Tris-HCl, 0.1 M NaCl, 37 degrees C): serotonin, 1.2; tryptamine, 2.9; 5-fluorotryptamine, 4.4; 6-fluorotryptamine, 7.2. At much higher levels, e.g. 10 mM, all of the above effectors, as well as indole, showed a moderate inhibition of human protein C activation. ATP, a platelet release product, showed a sigmoidal inhibition pattern similar to that found previously for thrombin amidase, clotting, and esterase activity (Conery, B.G., and Berliner, L.J. (1983) Biochemistry 22, 369-375). Overall, the enhancement factors for human alpha-thrombin activation of protein C with the tryptamine analogs described above were remarkable when considering the effect of a simple ligand versus the natural activator, thrombomodulin.
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PMID:Ligands which effect human protein C activation by thrombin. 365 43

In separate experiments, antibodies to plasminogen, factor X and protein C were applied to microtitre trays as commonly used in enzyme-linked immunoassays. After incubation with dilute normal human plasma as a source of the corresponding proenzyme antigen, the wells were exposed to dilutions of various snake venoms. After thorough washing, the microtitre tray wells were tested overnight with chromogenic tripeptide substrates known to be relatively specific for the activated forms of the above factors, i.e., plasmin, factor Xa and activated protein C. The immunochromometric assay described detected two new activators of protein C in Agkistrodon piscivorus and Agkistrodon contortrix venoms and a new factor X activator in Agkistrodon rhodostoma venom. Gel filtration of the latter venom indicated that the factor X activator eluted with high molecular weight, was clearly distinct from the peak fibrinogen clotting activity (Ancrod) and appeared to have no procoagulant activity. Although several Bothrops venoms appeared to contain plasminogen activator by this technique, the observed strong chromogenic activity was observed in microtitre wells independently of plasminogen and represented nonspecific amidase activity.
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PMID:Detection of specific proenzyme activators in snake venoms by a new immunoabsorbant-chromogenic substrate method. 384 Oct 12

Ecamulin, a novel prothrombin activating enzyme, has been isolated and purified 63-fold with a 57% yield from the venom of the Middle-Asian sand viper Echis multisquamatus using three-step ion-exchange chromatography. The enzyme was shown to activate prothrombin similarly to Ecarin, a prothrombin-converting enzyme from Echis carinatus venom, however, differing from the latter by structural and physico-chemical properties. The enzyme is a Zn-proteinase: it contains 1 mol Zn per 1 mol of protein. The molecular mass of the enzyme as determined by Sephacryl S-200 chromatography is 93 +/- 2 kDa. Upon SDS-PAAG electrophoresis ecamulin produces two bands with Mr of 67 and 27 kDa under non-reducing conditions, and three bands with Mr of 67, 14 and 13 kDa in the presence of DTT. During native PAGE without SDS, the activator yields one slow mobility band: two bands are observed after addition of DTT or EDTA. Carbohydrates containing N-acetyl-alpha-D-glucosamine residues are localized in the 67 kDa chain. Ecamulin has two isoforms, S2 and S3, that are distinguished by the charge and partial coagulation activities: form S2 has 250 NIH units/mg, while the S3 form has 524 NIH units/mg. The amino acid sequences of the both isoforms are similar but the more active S3 form has 4 times higher content of Gln and 4 times less of Gly than the S2 form. The isoelectric point is 4.3-4.5; E280 of 1% solution is 10.2. Forms S2 and S3 of ecamulin hydrolyze chromogenic substrates of plasma kallikrein S2302 and glandular kallikrein 2266. Ecamulin does not hydrolyze BAEE, TAME, LEE, thrombin substrates Chromozym TH and S2160, factor Xa-S2222, protein Ca-Chromozym PCa and Plasmin S2251. The amidase activity is nonreversibly inhibited by EDTA, o-phenanthroline (the activity is recovered by addition of Zn2+), Cys or DTT, EGTA, DFP, PMSF or pCMB do not inhibit the enzyme activity. Ecamulin converts prothrombin to alpha-thrombin passing by a shunt via the meizothrombin stage. The reaction of prothrombin activation does not require Ca2+, phospholipids of factor Va. Part of this work was presented at the International Conference "Fibrinogen and fibrinolysis", Yalta, September 23-28, 1995.
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PMID:[Isolation and characteristics of ekamulin--a prothrombin activator from multiscaled viper (Echis multisquamatus) venom]. 901 Dec 45

A method of overall haemostasis potential (OHP) determination for quantitative and rapid estimation of coagulation-fibrinolysis balance in plasma has been presented. The method is based on the analysis of the absorbance at 350 nm vs. time curve, which records the clot formation and dissolution in plasma in the presence of thromboplastin and t-PA. Three parameters of coagulation system--time, rate of formation and maximal turbidity of the clot, and three parameters of fibrinolytic system--half-, full-time and maximal rate of the clot dissolution, and main integral parameter--the area under the curve that characterizes the size and time of the clot existence and expresses OHP of plasma, can be determined by this method. It was shown that OHP value of patients plasma was 3.8 times more than that of the donor plasma. It is in concordance with elevated level of Fg (4.25 mg/ml), soluble fibrin (50 microg/ml), D dimer (630 ng/ml) and insufficient decrease of APC activity (93%) in patients. AcPC, added to donor and patient plasma, reduced OHP value 1.6 and 3.7 times, correspondingly. AcPC increased amidase activity of thrombin and APC in the donor plasma, and did not change that of plasmin. These data indicated that the effect of AcPC on OHP is mediated by formation ofAPC that helps to reduce the level of inhibitors in the investigated plasma.
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PMID:[Effect of protein C activator on overall haemostasis potential in donor and hip arthroplasty patient plasma]. 2227 26

The complement system is a key component of the host immune response for the recognition and clearance of Streptococcus pneumoniae. In this study, we demonstrate that the amidase LytA, the main pneumococcal autolysin, inhibits complement-mediated immunity independently of effects on pneumolysin by a complex process of impaired complement activation, increased binding of complement regulators, and direct degradation of complement C3. The use of human sera depleted of either C1q or factor B confirmed that LytA prevented activation of both the classical and alternative pathways, whereas pneumolysin inhibited only the classical pathway. LytA prevented binding of C1q and the acute-phase protein C-reactive protein to S. pneumoniae, thereby reducing activation of the classical pathway on the bacterial surface. In addition, LytA increased recruitment of the complement downregulators C4BP and factor H to the pneumococcal cell wall and directly cleaved C3b and iC3b to generate degradation products. As a consequence, C3b deposition and phagocytosis increased in the absence of LytA and were markedly enhanced for the lytA ply double mutant, confirming that a combination of LytA and Ply is essential for the establishment of pneumococcal pneumonia and sepsis in a murine model of infection. These data demonstrate that LytA has pleiotropic effects on complement activation, a finding which, in combination with the effects of pneumolysin on complement to assist with pneumococcal complement evasion, confirms a major role of both proteins for the full virulence of the microorganism during septicemia.
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PMID:Pleiotropic effects of cell wall amidase LytA on Streptococcus pneumoniae sensitivity to the host immune response. 2540 32

The spirochete Borrelia burgdorferi survives in its tick vector, Ixodes scapularis, or within various hosts. To transition between and survive in these distinct niches, B. burgdorferi changes its gene expression in response to environmental cues, both biochemical and physiological. Exposure of B. burgdorferi to weak monocarboxylic organic acids, including those detected in the blood meal of fed ticks, decreased the cytoplasmic pH of B. burgdorferi in vitro. A decrease in the cytoplasmic pH induced the expression of genes encoding enzymes that have been shown to restore pH homeostasis in other bacteria. These include putative coupled proton/cation exchangers, a putative Na+/H+ antiporter, a neutralizing buffer transporter, an amino acid deaminase and a proton exporting vacuolar-type VoV1 ATPase. Data presented in this report suggested that the acid stress response triggered the expression of RpoN- and RpoS-dependent genes including important virulence factors such as outer surface protein C (OspC), BBA66, and some BosR (Borrelia oxidative stress regulator)-dependent genes. Because the expression of virulence factors, like OspC, are so tightly connected by RpoS to general cellular stress responses and cell physiology, it is difficult to separate transmission-promoting conditions in what is clearly a multifactorial and complex regulatory web.
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PMID:Weak Organic Acids Decrease Borrelia burgdorferi Cytoplasmic pH, Eliciting an Acid Stress Response and Impacting RpoN- and RpoS-Dependent Gene Expression. 2903