Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The E fragment, derived from the NH2-terminal aspect of fibrinogen by plasmin cleavage (fg-E), possesses two generically distinct sets of antigenic expressions. The major set of antigens is expressed by the parent molecule as indicated by the capacity of a major subpopulation of antibodies present in antiserum to fg-E and reactive with fg-E to: (a) react with fibrinogen, and (b) be specifically absorbed by fibrinogen but appears following proteolysis with plasmin. These cleavage associated neoantigens (fg-E-neo) specifically react with a minor subpopulation of antibodies present in antiserum to fg-E.E fragments isolated after varying exposures to plasmin all expressed fg-E-neo, but early E fragments exhibited quantitatively less neoantigenic expression than more extensively degraded E fragments. The entire fg-E-neo expression is recovered on a single isolated constituent chain of the E fragment, and immunochemical analysis with antiserum to the isolated constituent chain-bearing fg-E-neo identifies it as a derivative of the gamma chain constituent, exhibits marked stability to physicochemical denaturation and enzymatic degradation. These properties suggest that the neoantigen may be associated with a specific amino acid sequence which is exposed by the cleavage process. The identification and localization of fg-E-neo provides a specific molecular marker site for the characterization of structural and conformational changes associated with catabolism and function of fibrinogen.
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PMID:A cleavage-associated neoantigenic marker for a gamma chain site in the NH2-terminal aspect of the fibrinogen molecule. 4 27

Conformational and structural modulations of the NH2-terminal region of fibrinogen and fibrin associated with plasmin cleavage have been examined utilizing specific antibody probes. The E region derived from the NH2-terminal aspects of fibrinogen undergoes complex structural and conformational changes throughout the cleavage process as indicated by differences in the quantitative and qualitative expression of antigenic determinants by the E region of each isolated cleavage fragment. When the range of antigenic determinants recognized by the antibody probe is limited to a specific molecular marker on the gamma chain within the E region, fg-E-neo, evidence for a systematic and progressive modulation of this site during plasmin cleavage is observed. Fg-E-neo undergoes progressive exposure as the cleavage of fibrinogen proceeds from X to Y to D:E complex. Separation of the D:E complex into its constituent, D and E fragments, is associated with further exposure of fg-E-neo determinants. The sequential cleavage of fibrin by plasmin also leads to progressive exposure of the fg-E-neo site; however, comparison of corresponding fragments derived from fibrinogen and fibrin reveals significant differences in the character of fg-E-neo expression. Immunochemical differences between fibrin and fibrinogen E fragments are not abolished by further exposure of the fragments to plasmin, are apparently not due to the presence or absence of fibrinopeptides, and are maintained following denaturation and renaturation of the fragments. These results suggest that the differential expression of fg-E-neo by the E fragments may be primarily dependent upon differences in amino acid compositions of the fragments.
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PMID:Conformational and structural modulation of the NH2-terminal regions of fibrinogen and fibrin associated with plasmin cleavage. 4 28

1. The factor XIII-mediated cross-linked alpha chains in fibrin have no effect on the nature of the fragments released during the solubilization of fibrin by plasmin. 2. Besides the known D dimer and E fragments solubilized during the lysis of cross-linked fibrin, other fragments have been observed on sodium dodecyl sulphate-polyacrylamide gel electrophoresis which have a molecular weight of about 135 000. After prolonged plasmin digestion, these fragments (U fragments) were no longer evident on the gels and the high-molecular-weight E antigen was absent. It is assumed that the E antigen was associated with the U fragments. These fragments also cross-reacted with an anti-D serum. 3. The U fragments have been tentatively presumed to be a factor XIII-mediated cross-linked D-E complex since they degrade only after prolonged degradation with plasmin. Whereas it is known that the fibrin D dimer fragment contains the cross-linked gamma chain residues of the originating fibrin, the presumed covalent cross-linking of the D-E fragments has not been proved. 4. The presence of these high-molecular-weight fragments, containing the E antigen, in cross-linked human fibrin digests should be taken into account in the development of D dimer assays to monitor fibrin lysis in vivo.
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PMID:Soluble high-molecular-weight E fragments in the plasmin-induced degradation products of cross-linked human fibrin. 12 78

Fragment D has been isolated as an apparently single molecular weight species (molecular weight about 100,000) from plasmin digests of humman fibrinogen, using a combination of affinity chromatography on insolubilized "fibrin monomer" and gel filtration. This fragment consists of three chains with molecular weights of 15,000 (Dbeta), 42,500 (Dgamma1) or 39,500 (Dgamma2), and 14,000 (Dalpha) held together by disulfide bonds. The S-carboxymethyl derivatives of the chains have been separated by gel filtration and ion exchange chromatography, and their identity has been confirmed by peptide mapping and immunological analysis. The chain with a molecular weight of 45,000 is a fragment of the Bbeta chain of fibrinogen. The chain derived from the gamma chain of fibrinogen occurred in two molecular forms having molecular weight 42,500 and 39,500. The chain derivative with molecular weight 14,000 is most likely derived from the Aalpha chain of fibrinogen. The chains were characterized by NH2-terminal sequence analysis, amino acid composition, and carbohydrate staining. The two molecular analysis, amino acid composition, and carbohydrate staining. The two molecular forms of the gamma chain appeared to be identical except for an NH2-terminal peptide extension of 23 amino acid residues in the longer chain. The latter has sequences in common with the COOH-terminal part of the gamma chain of the NH2-terminal disulfide knot (BROMBACK, B., BRONDAHL, N. J., HESSEL, B., IWANAGA, S., and WALLEN, P. (1973) J. Biol. Chem. 248, 5806-5820); its NH2-terminal residue being Ala-63 of the gamma chain of fibrinogen.
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PMID:Primary structure of human fibrinogen and fibrin. Isolation and partial characterization of chains of fragment D. 12 79

Three Fragment D species (D1, D2, D3) were isolated with time from a plasmin digest of fibrinogen and had molecular weights of 92,999, 86,000 and 82,000 by summation of subunit molecular weights from sodium dodecyl sulfate polyacrylamide gel electrophoresis. Their molecular weights by sedimentation equilibrium ultracentrifugation were 94,000 t87,000, 88,000 to 82, 000, and 76,000 to 70,000 depending on the values calculated for the partial specific volumes. Each of the Fragment D species contained three disulfide-linked subunits derived from the Aalpha, Bbeta, and gamma chains of fibrinogen and differed only in the extent of COOH-terminal degradation of their gamma chain derivatives. Plasmin cleaved Fragment D1 to release the cross-link sites from its gamma' subunit of 38,000 molecular weight; however, the beta'' subunit of 42,000 molecular weight and the alpha'' subunit of 12,000 molecular weight were resistant to further digestion by plasmin. Fragment D isolated from highly cross-linked fibrin had a dimeric structure due to cross-link formation between the gamma' subunits of two fibrinogen Fragment D species. The molecular weight of fibrin Fragment D was 184,000 by summation of subunit molecular weights and 190,000 to 175,000 by sedimentation equilibrium. Cross-linking the gamma chain, as well as incorporating the site-specific fluorescent label monodansyl cadaverine into the gamma chain cross-link acceptor site, prevented its COOH-terminal degradation by plasmin. Therefore, only one species of fibrin Fragment D, as well as only one species of monodansyl cadaverine-labeled fibrin Fragment D monomer, was generated during plasmin digestion. These results show unequivocally that each fibrinogen Fragment D contains only three subunit chains and therefore the digestion of fibrinogen by plasmin must result in the production of two Fragment D molecules from each fibrinogen molecule. The recently proposed model of fibrinogen cleavage that postulates the generation of a single Fragment D with three pairs of subunit chains from each fibrinogen molecule is incorrect. Incorporation of monodansyl cadaverine into the cross-link acceptor sites of the alpha chain did not alter its cleavage by plasmin detectably. A series of monodansyl cadaverine-labeled peptides, which ranged in molecular weight from 40,000 to 23,000, were cleaved from the alpha chain of monodansyl cadaverine-labeled fibrin monomer during the early stages of plasmin digestion. These peptides were degraded progressively to a brightly fluorescent plasmin-resistant peptide of 21,000 molecular weight and a weakly fluorescent peptide of 2,500 molecular weight. Thus both alpha chain cross-link acceptor sites are contained within a peptide segment of 23,000 molecular weight.
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PMID:A re-examination of the cleavage of fibrinogen and fibrin by plasmin. 12 32

The molecular weight of Fragment D derivatives obtained from plasmic digests of fibrinogen and cross-linked fibrin was determined by equilibrium sedimentation and compared with the summated molecular weight of their polypeptide chains observed after electrophoresis of reduced protein in sodium dodecyl sulfate polyacrylamide gels. The measured molecular weight of Fragment D (Stage 2) of fibrinogen is 103 500, which is compatible with a molecule containing only one each of the Aalpha (13 000), Bbeta (43 000) and gamma (39 000) chain remnants. Fragment D-D of cross-linked fibrin has a molecular weight of 189 000, compatible with a molecule containing one isopeptide-bound gamma-gamma chain (80 000) and two each of Bbeta (43 000) and Aalpha (13 000) chain remnants. The NH2-terminal amino acid residues of the Fragment D derivatives were measured quantitatively using a thioacetic-thioglycolic acid method, and molar quantities were calculated on the basis of the molecular weights determined by equilibrium sedimentation. Fragment D preparations obtained from Stage 2 and Stage 3 digests of fibrinogen have 3 mol of NH2-terminal amino acids per molecule, while Fragment D-D has seven. These data support the view that two Fragment D molecules, each of three polypeptide chains, are derived by plasmic degradation from each fibrinogen molecule, and that an isopeptide-bound, six chain Fragment D-D molecule is released from cross-linked fibrin by plasmin. Equlibrium sedimentation measurement of the molecular weights of Fragment X (Stage 1 and Stage 2) and Fragment Y are 265 000 and 148 000, respectively. These values are compatible with asymmetric cleavages of Fragment X to Fragments Y and D (Stage 2), and of Fragment Y to Fragments D (Stage 2) and E, and with a fibrinogen model in which the two halves are joined by disulfide bonds only in the amino-terminal regions.
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PMID:Comparison of the physicochemical properties of fragment D derivatives of fibrinogen and fragment D-D of cross-linked fibrin. 13 Sep 27

Fragment E, a terminal plasmin digestion product of fibrinogen or fibrin, contains portions of the alpha, beta, and gamma chains linked by disulfide bonds. In this study, Fragment E from fibrinogen and fully cross-linked fibrin were purified by gel filtration of the soluble fraction from heated plasmin digests of either fibrinogen or fibrin or by step-wise chromatography of terminal plasmin digests of fibrinogen or cross-linked fibrin on DEAE-cellulose. Fibrinogen Fragment E and fibrin Fragment E migrated as single bands with identical mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis or on polyacrylamide gel electrophoresis at pH 3.2 or pH 8.6. After reduction by beta-mercaptoethanol, the two Fragment E species had very similar patterns on sodium dodecyl sulfate gel electrophoresis; each contained three subunits which had molecular weights ranging from 5,000 to 12,000. Only the subunit polypeptide derived from the gamma chain in either Fragment E contained carbohydrate. The two Fragment E species had identical sedimentation coefficients and identical molecular weights by equilibrium ultracentrifugation. The amino acid compositions were indistinguishable. Partial NH2-terminal sequence analyses of fibrinogen Fragment E and fibrin E were identical, indicating that plasmin had cleaved the NH2-terminal regions of the Aalpha or alpha and Bbeta or beta chains of both Fragment E Species.
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PMID:Characterization of fragment E from fibrinogen and cross-linked fibrin. 81 59

Binding of the adhesive ligand fibrinogen and the monoclonal antibody PAC1 to platelet glycoprotein (GP) IIb-IIIa is dependent on cell activation and inhibited by Arg-Gly-Asp (RGD)-containing peptides. Previously, we identified a sequence in a hypervariable region of PAC1 (mu-CDR3) that mimics the activity of the antibody. Here we examine whether monoclonal antibodies to this idiotypic determinant in PAC1 can mimic GP IIb-IIIa by binding to fibrinogen. Mice were immunized with a peptide derived from the mu-CDR3 of PAC1. Four antibodies were obtained that recognized fibrinogen as well as a recombinant form of the variable region of PAC1. However, they did not bind to other RGD-containing proteins, including von Willebrand factor, fibronectin, and vitronectin. Several studies suggested that these anti-PAC1 peptide antibodies were specific for GP IIb-IIIa recognition sites in fibrinogen. Three such sites have been proposed: two RGD-containing regions in the A alpha chain, and the COOH terminus of the gamma chain (gamma 400-411). Two of the antibodies inhibited fibrinogen binding to activated platelets, and all four antibodies bound to the fibrinogen A alpha chain on immunoblots. Antibody binding to immobilized fibrinogen was partially inhibited by monoclonal antibodies specific for the two A alpha chain RGD regions. However, the anti-PAC1 peptide antibodies also bound to plasmin-derived fibrinogen fragments X and D100, which contain gamma 400-411 but lack one or both A alpha RGD regions. This binding was inhibited by an antibody specific for gamma 400-411. When fragment D100 was converted to D80, which lacks gamma 400-411, antibody binding was reduced significantly (p less than 0.01). Electron microscopy of fibrinogen-antibody complexes confirmed that each antibody could bind to sites on the A alpha and gamma chains. These studies demonstrate that certain anti-PAC1 peptide antibodies mimic GP IIb-IIIa by binding to platelet recognition sites in fibrinogen. Furthermore, they suggest that the gamma 400-411 region of fibrinogen may exist in a conformation similar to that of an A alpha RGD region of the molecule.
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PMID:Anti-idiotypic antibodies against an antibody to the platelet glycoprotein (GP) IIb-IIIa complex mimic GP IIb-IIIa by recognizing fibrinogen. 137 Aug 32

Human fibrinogen and the plasmin-generated fibrinogen fragment D were photoaffinity labeled specifically with the peptide [14C]Gly-Pro-Arg-N(4-azido-2-nitrophenyl)Lys amide. In the case of fibrinogen, greater than 85% of the incorporated radioactivity was found in the gamma chain. Similarly, when fragment D (Mr, 90,000) was labeled with the same derivatized peptide, virtually all the radioactivity was found in the gamma-chain portion. The labeled fragment D was treated with CNBr and an initial purification was achieved by two gel-filtration steps. The labeled material was purified further by HPLC and was also compared with CNBr digests of unlabeled material. Amino acid analysis and gas-phase sequencing showed the labeled fragment to be gamma-chain residues 337-379.
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PMID:Photoaffinity labeling of the primary fibrin polymerization site: isolation and characterization of a labeled cyanogen bromide fragment corresponding to gamma-chain residues 337-379. 155 95

The interaction between the binding site of a polysaccharide (called compact colony forming active substance (CCFAS)), obtained from the cell surface of a strain of Staphylococcus, and human fibrinogen (HF) was investigated. The CCFAS was found to bind specifically to both the B beta and gamma chains of HF at pH 7.0 and 8.0, and the A alpha chain at pH 5.0. The binding of CCFAS with fibrinogen fragments obtained by digestion with plasmin were also investigated. Fragments with Mr of 55,000, 24,000, and 19,000 were the major bands precipitated by CCFAS at pH 7.0 and 8.0. Fragments with Mr of 85,000 and 75,000 bound to CCFAS at pH 5.0. Binding of CCFAS (7 micrograms) with fibrinogen could be inhibited by 1.2 micrograms of B beta chain and 1.5 micrograms gamma chain at alkaline pH or 6.2 micrograms of the A alpha chain at pH 5.0. CCFAS was, therefore, assumed to be specifically bonded with HF molecules, in the alkaline range at least, resulting in compact colony forming activity in serum soft agar and paracoagulation.
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PMID:Binding of staphylococcal cell surface polysaccharide to human fibrinogen. 214 Feb 87


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