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:3.4.21.5 (thrombin)
33,306 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The results of this paper indicate that cattle infected with B. bovis (argentina) have a markedly altered and activated coagulation system. A degree of thrombin activation occurs due partly to release of thromboplastin-like substances from lysed erythrocytes but due primarily to activation of kallikrein by babesial proteases. This produces a hyperfibrinogenaemia, particularly in intact cattle, with soluble fibrin complexes constituting up to one-third of the total fibrinogen concentration. High molecular weight non-coagulable fibrinogen-like proteins are detected terminally but more so in splenectomized cattle. Plasminogen concentration decreases in splenectomized but not intact cattle while low molecular weight fibrinogen degradation products are not easily detected. It is suggested that a hypercoagulable intermediate state with little or no fibrin deposition occurs rather than terminal disseminated intravascular coagulation.
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PMID:Babesia bovis (argentina): observations of coagulation parameters, fibrinogen catabolism and fibrinolysis in intact and splenectomized cattle. 60 70

The interaction of the following human fibrinogen-like peptides with bovine thrombin was studied by use of one- and two-dimensional NMR techniques in aqueous solution: Ala(1)-Asp-Ser-Gly-Glu-Gly-Asp-Phe(8)-Leu-Ala-Glu-Gly-Gly-Gly-Val-Arg(16 )- Gly(17)-Pro-Arg(19)-Val(20)-Val-Glu-Arg (F10), residues 1-16 of F10 (fibrinopeptide A), residues 17-23 of F10 (F12), residues 1-20 of F10 (F13), residues 6-20 of F10 with Arg(16) replaced by a Gly residue (F14), and residues 6-19 of F10 with Arg(16) replaced by a Leu residue (F15). At pH 5.3 and 25 degrees C, the Arg(16)-Gly(17) peptide bonds of both peptides F10 and F13 were cleaved instantaneously in the presence of 0.6 mM thrombin, whereas the cleavage of the Arg(19)-Val(20) peptide bonds in peptides F12, F13, and F14 took over 1 h for completion. On the basis of observations of line broadening, fibrinopeptide A was found to bind to thrombin. While resonances from residues Ala(1)-Glu(5) were little affected, binding of fibrinopeptide A to thrombin caused significant line broadening of NH and side-chain proton resonances within residues Asp(7)-Arg(16). There is a chain reversal within residues Asp(7)-Arg(16) such that Phe(8) is brought close to the Arg(16)-Gly(17) peptide bond in the thrombin-peptide complex, as indicated by transferred NOEs between the aromatic ring protons of Phe(8) and the C alpha H protons of Gly(14) and the C gamma H protons of Val(15). A similar chain reversal was obtained in the isolated peptide F10 at a subzero temperature of -8 degrees C. The titration behavior of Asp(7) in peptide F13 does not deviate from that of the reference peptide, N-acetyl-Asp-NHMe at both 25 and -8 degrees C, indicating that no strong interaction exists between Asp(7) and Arg(16) or Arg(19). Peptides with Arg(16) replaced by Gly and Leu, respectively, i.e., F14 and F15, were also found to bind to thrombin but with a different conformation, as indicated by the absence of the long-range NOEs observed with fibrinopeptide A. Residues Asp(7)-Arg(16) constitute an essential structural element in the interaction of thrombin with fibrinogen.
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PMID:High-resolution NMR studies of fibrinogen-like peptides in solution: interaction of thrombin with residues 1-23 of the A alpha chain of human fibrinogen. 274 26

The interaction of the following human fibrinogen-like peptides with bovine thrombin was studied by one- and two-dimensional NMR techniques in aqueous solution: acetyl-Phe(8)-Leu(9)-Ala(10)-Glu-(11)-Gly(12)-Gly(13)-Gly(14)-Val(15)-Ar g(16)- Gly(17)-Pro(18)-NHMe (F6), acetyl-Phe-Leu-Ala-Glu-Gly-Gly-Gly-Val-Arg(16) (tF6), acetyl-Asp(7)-Phe-Leu-Ala-Glu-Gly-Gly-Gly-Val-Arg(16)-Gly(17)-Pro- Arg(19)-Val(20)-NHMe (F8), and acetyl-Asp-Phe-Leu-Ala-Glu-Gly-Gly-Gly-Val-Arg(16) (tF8). At pH 5.3 and 25 degrees C, the Arg(16)-Gly(17) peptide bonds in both F6 and F8 were cleaved instantaneously in the presence of 0.5 mM thrombin, producing truncated peptides tF6 and tF8 and other peptide fragments. On the basis of observations of line broadening, thrombin was found to bind to the cleavage products, tF6 and tF8, of peptides F6 and F8. Peptide tF8 may have a higher affinity for thrombin than peptide tF6, as suggested by the more pronounced thrombin-induced line broadening on the proton resonances in peptide tF8. Transferred NOE (TRNOE) measurements were made of the complexes between thrombin and peptides tF6 and tF8. Medium- and long-range NOE interactions were found between the NH proton of Asp(7) and the C beta H protons of Ala(10), between the C alpha H proton of Glu(11) and the NH proton of Gly(13), and between the ring protons of Phe(8) and the C alpha H protons of Gly(14) and the C gamma H protons of Val(15). Sets of structures of the decapeptide tF8 were deduced by use of distance geometry calculations based on sequential and medium- and long-range TRNOEs from the thrombin-bound peptide. A predominant feature of these structures is the nonpolar cluster formed by the side chains of residues Phe(8), Leu(9), and Val(15) that are directly involved in binding to thrombin. This structural feature is brought about by an alpha-helical segment involving residues Phe(8)-Ala(10), followed by a multiple-turn structure involving residues Glu(11)-Val(15). These results provide an explanation for the observations that Asp(7), Phe(8), and Gly(12) are strongly conserved in mammalian fibrinogens and that the mutations of Asp(7) to Asn(7) and of Gly(12) to Val(12), result in delayed release of fibrinopeptide A, producing human bleeding disorders.
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PMID:High-resolution NMR studies of fibrinogen-like peptides in solution: structure of a thrombin-bound peptide corresponding to residues 7-16 of the A alpha chain of human fibrinogen. 274 27

In human fibrinogen Rouen, which is the origin of a bleedin disorder, a single amino acid is mutated from Gly(12) to Val(12) in the A alpha chain. In the previous paper of this series, this mutation was predicted to disrupt the structure of fibrinogen-like peptides bound to bovine thrombin. The structural basis of this bleeding disorder has been further assessed by studying the interaction of the following Val(12)-substituted human fibrinogen-like peptides with bovine thrombin in aqueous solution by use of two-dimensional NMR spectroscopy (including TRNOE): Ala-Asp-Ser-Gly-Glu-Gly-Asp(7)-Phe-Leu-Ala- Glu-Val(12)-Gly-Gly-Val-Arg(16)-Gly(17)-Pro-Arg-Val-NH2 (F16), Ala-Asp-Ser-Gly-Glu-Gly-Asp(7)-Phe-Leu-Ala-Glu-Val(12)-Gly-Gly-Val- Arg(16) (tF16), Ala-Asp-Ser-Gly-Glu-Cys(Acm)-Asp(7)-Phe-Leu-Ala-Glu-Val(12)-Gly-Gly-Val- Arg(16)-Gly(17)-Pro-Arg-Val-Cys(Acm)-NH2 (F17), and Ala-Asp-Ser-Gly-Glu-Cys(Acm)-Asp(7)-Phe-Leu-Ala-Glu-Val(12)-Gly-Gly- Val-Arg(16) (tF17). Binding of thrombin to peptides F16 and F17, and hence to tF16 and tF17 as a result of the cleavage of the Arg(16)-Gly(17) peptide bond, broadens the proton resonances of residues Asp(7) to Arg(16), suggesting that thrombin interacts specifically with this sequence of residues. Medium- and long-range TRNOE's were observed between the NH proton of Asp(7) and the C beta H protons of Ala(10) and between the ring protons of Phe(8) and the C gamma H protons of Val(12) and Val(15) in complexes of thrombin with both tF16 and tF17. A strong TRNOE, in peptides tF16 and tF17, between the C beta H protons of Glu(11) and the backbone NH proton of Val(12) was also observed. However, TRNOE's between the ring protons of Phe(8) and the C alpha H protons of Gly(14) and between the C alpha H proton of Glu(11) and the NH proton of Gly(13), previously observed in the complex of thrombin with FpA, were absent in both peptides tF16 and tF17. From incorporation of TRNOE information into distance geometry calculations, Val(12) was found to disrupt the type II beta-turn involving Glu(11) and Gly(12) that is present in complexes of thrombin with normal fibrinogen-like peptides. The positions of Gly(13) and Gly(14) in the complex are also displaced, relative to the aromatic ring of Phe(8), by the Val(12) substitution. This altered geometry presumably affects the positioning of the Arg(16)-Gly(17) bond in the active site of thrombin.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:High-resolution NMR studies of fibrinogen-like peptides in solution: structural basis for the bleeding disorder caused by a single mutation of Gly(12) to Val(12) in the A alpha chain of human fibrinogen Rouen. 274 28

The proton resonances of the following synthetic linear human fibrinogen-like peptides were completely assigned with two-dimensional NMR techniques in solution: Ala(1)-Asp-Ser-Gly-Glu-Gly-Asp(7)-Phe-Leu-Ala-Glu-Gly(12)-Gly(13)-Gly(14)- Val(15)-Arg(16)-Gly-Pro-Arg-Val-Val-Glu-Arg (F10), Ala-Asp-Ser-Gly-Glu-Gly-Asp-Phe-Leu-Ala-Glu-Gly-Gly(13)-Gly(14)-Val-Arg (F11), and Gly-Pro-Arg-Val-Val-Glu-Arg (F12). No predominant structure was found in the chain segment from Ala(1) to Gly(6) for F10 in both H2O and dimethyl sulfoxide. The previous suggestion that there is a hairpin loop involving residues Gly(12) to Val(15) in the A alpha chain of human fibrinogen is supported by the slow backbone NH exchange rates of Gly(14) and Val(15), by an unusually small NH chemical shift of Val(15), and by strong sequential NOE's involving this region in F10. This local chain fold within residues Asp(7) to Val(20) may place the distant Phe residue near the Arg(16)-Gly(17) peptide bond which is cleaved by thrombin.
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PMID:High-resolution NMR studies of fibrinogen-like peptides in solution: resonance assignments and conformational analysis of residues 1-23 of the A alpha chain of human fibrinogen. 316 91

The following synthetic linear A alpha fibrinogen-like peptides were studied by NMR spectroscopy in aqueous solution: Ac-Asp(P10)-Phe(P9)-Leu-Ala-Glu-Gly(P5)-Gly(P4)-Gly(P3)-Val- Arg(P1)-Gly-(P1)-Pro-Arg(P3')-Val-NHCH3 (F-8), Ac-Phe-Leu-Ala-Glu-Gly-Gly(P4)-Gly(P3)-Val-Arg-Gly-Pro-NHCH3 (F-6), Ac-Leu-Ala-Glu-Gly-Gly(P4)-Gly(P3)-Val-Arg-Gly-Pro-NHCH3 (F-7), and Ac-Gly-Gly(P4)-Gly-(P3)-Val-Arg-Gly-Pro-NHCH3 (F-9). The temperature dependence of the amide proton chemical shift is smaller by approximately 22% for the Gly(P3) amide proton in F-9, F-6, and F-8 and is similarly smaller for the Gly(P4) amide proton in F-6 and F-8, but not F-9, relative to the other amide protons in these peptides. The exchange rates with solvent water for the Gly(P3) amide proton in each of these four peptides were determined by solvent spin saturation transfer experiments. The exchange rate constant for the Gly(P3) amide proton of F-8 was half that of the rate constant determined for this proton in F-9, F-7, and F-6. In conjunction with previously reported data for the rate of hydrolysis of the Arg(P1)-Gly(P1') bond by thrombin, these results suggest that there is a beta-bend at Gly(P5)-Gly(P4), possibly stabilized by salt links between Asp(P10) and Arg(P3') and between phosphorylated Ser(P14) and Arg(P7'), which brings Phe(P9) close to the hydrolyzable Arg-Gly bonds.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mechanism of action of thrombin on fibrinogen: NMR evidence for a beta-bend at or near fibrinogen A alpha Gly(P5)-Gly(P4). 402 28

In a study of the action of thrombin on fibrinogen and a comparison of this enzyme with trypsin, several fibrinogen-like oligopeptides were synthesized. The hydrolysis of the arginyl-glycine bond in these peptides, by both of these enzymes, is examined and compared.
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PMID:Mechanism of action of thrombin on fibrinogen. I. Synthesis of fibrinogen-like peptides, and their proteolysis by thrombin and trypsin. 527 64

Accumulation of lipid in developing fibrous atherosclerotic plaques is associated with high concentrations of fibrin and accumulation of a tightly bound lipoprotein fraction that can be released by incubation with fibrinolytic enzymes, suggesting that fibrin may play a key role in lesion development. It is not known whether this fibrin represents incorporated mural thrombus or is produced in situ by clotting of the fibrinogen that is present in intima in high concentration. Immunoelectrophoresis was used to measure the concentrations of fibrinogen and components of the clotting system in human aortic intima and lesions, and in mural thrombi. In the lipid and fibrin rich plaque centres prothrombin concentration was almost twice that in normal intima, but concentrations of the thrombin inhibitors antithrombin III and alpha 2-macroglobulin fell, so that the molar ratios of inhibitor/prothrombin fell from 3:1 in normal intima to 1:1 in the plaque centre. In mural thrombi there was preferential sequestration of fibrinogen-like antigen and prothrombin. Distribution of factor-VIII-related antigen was highly unpredictable; in both normal intima and all types of intimal lesion substantial amounts were recovered from some samples, whereas none was recovered from others. The highest concentrations were found in samples free of endothelium from the deep layers of lesions. The results are compatible with the idea that fibrinogen may be converted to fibrin within lesions; once some fibrin has accumulated within the intima it seems to bind low-density lipoprotein and sequester fibrinogen and clotting factors, thereby producing a self-amplifying system.
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PMID:Haemostatic factors in human aortic intima. 611 25

This investigation was conducted to examine the presence of fibrinogen-like substance and thrombin-like enzyme in human semen (human seminal plasma) after liquefaction. The human seminal plasma contained small amounts of respective substances which are absorbed on anti-fibrinogen and anti-thrombin III affinity columns, respectively. The thrombin-like enzyme with Gly-Pro-Arg-pNA amidolytic activity was inhibited by human seminal plasma trypsin-like enzyme inhibitor (HSP-TI) and antithrombin III. The fibrinogen-like substance reacted with the thrombin-like enzyme, forming a fibrin-like substance. It would appear that certain aspects of the coagulation process in human semen constitute the same process as the final stage of the blood coagulation system.
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PMID:Fibrinogen-like substance and thrombin-like enzyme in seminal plasma: coagulation system of human semen. 901 20

To examine whether fibrin N-terminal Aalpha 17-23 and Bbeta 15-25 may contain high-affinity polymerization sites, GPRVVER and GHRPLDKKREE analogs were prepared, and their abilities to inhibit fibrin monomers from repolymerizing were compared in turbidity and clottability assays. Within Aalpha 17-23, GPR is the most active site (IC30 of 0.95-1.36 mM). Its extension into GPRVVER (IC30 of 1.75-2.3 mM) reduced activity. Within Bbeta 15-25, acyl-DKKREE (IC30 of 0.30-0.53 mM) can account for GHRPLDKKREE activity (IC30 of 0. 33-0.44 mM). Comparison of the assays showed that calcium, whose presence induces thick fibrin fibers, elicited a higher turbidity than clottability inhibition. Similarly, the lateral-association-promoting GHRP (IC30 of 1.25-1.43 mM) gave a high turbidity vs clottability inhibition ratio (137%). In contrast, low ratios were found for the linear-association-initiating GPR (73%) and for acyl-DKKREE (34%). Structure-activity correlation showed that fibrinogen-like acyl-GPRP and acyl-GHRP could inhibit D. E association at the millimolar range, but in a manner different from fibrin-related GPR peptides did, which required the NH2 as well as Arg presence. To explain Bbeta 20-25 masking, it is proposed that DKKREE in fibrinogen may engage in ionic and hydrogen bonds with KDSDW, the Aalpha 29-33 sequence implicated in thrombin binding. To explain acyl-GPRP and acyl-GHRP inhibition of D.E association, it is proposed that fibrinogen packing may be mediated by E domain association with alphaC (Aalpha 220-609) fragments of adjacent molecules, and by alphaC-alphaC association. A modified polymerization mechanism is deduced by taking into account fibrinogen N-terminal conformation as well as E domain binding to thrombin vs alphaC fragments. This model proposes the following. (1) Upon thrombin binding to fibrinogen KDSDW, DKKREE may become exposed. (2) Fibrinopeptide A cleavage further unmasks the NH2 and Arg group of GPR, leading to DKKREE and GPR initiation of polymerization. (3) The micromolar-effective thrombin-fibrin(ogen) binding may initiate a partial alphaC repulsion. Subsequent DKKREE and GPR binding to D domains of other fibrin(ogen) will lead to the formation of the trimer and bring additional molecules to fibrin N-terminal region, and the combined steric congestion may lead to a complete alphaC repulsion from the overcrowded E domain. (4) Repulsion of the large Aalpha 220-609 fragments may unmask multiple polymerization sites beyond the fibrin N-terminal region.
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PMID:Localization of an effective fibrin beta-chain polymerization site: implications for the polymerization mechanism. 923 81


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