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P. Marchot - One of the best experts on this subject based on the ideXlab platform.

  • A fibrinogen-clotting serine proteinase from Cerastes cerastes (horned viper) venom with Arginine-Esterase and amidase activities. Purification, characterization and kinetic parameter determination
    Toxicon, 1992
    Co-Authors: Fatima Laraba-djebari, Marie-france Martin-eauclaire, P. Marchot
    Abstract:

    An enzyme displaying proteolytic activity toward the natural substrate casein as well as clotting activity on fibrinogen was purified to homogeneity from Cerastes cerastes (horned viper) venom and characterized. The enzyme is constituted of two identical subunits of mol. wt 48,500 as determined by SDS-polyacrylamide gel electrophoresis, and has an isoelectric point of 3.75. N-terminal sequencing up to the 33rd residue evidenced a high homology with other snake venom proteinases. The proteinase is of serine-type as indicated by high sensitivity to DFP and shows both Arginine-ester hydrolase and amidase activities on synthetic substrates. Both specific activities were 30-fold higher than the respective activities found in the crude venom. The Km value determined for Arginine-containing substrate BAEE was 3.0 x 10(-4) M and the Km for chromogenic substrate CBS 34-47 0.65 x 10(-4) M. The Vm/Km ratio, however, was two-fold higher for BAEE than for CBS 34-47; the Arginine-Esterase activity of this enzyme is thus slightly higher than its amidase activity.

Fatima Laraba-djebari - One of the best experts on this subject based on the ideXlab platform.

  • A fibrinogen-clotting serine proteinase from Cerastes cerastes (horned viper) venom with Arginine-Esterase and amidase activities. Purification, characterization and kinetic parameter determination
    Toxicon, 1992
    Co-Authors: Fatima Laraba-djebari, Marie-france Martin-eauclaire, P. Marchot
    Abstract:

    An enzyme displaying proteolytic activity toward the natural substrate casein as well as clotting activity on fibrinogen was purified to homogeneity from Cerastes cerastes (horned viper) venom and characterized. The enzyme is constituted of two identical subunits of mol. wt 48,500 as determined by SDS-polyacrylamide gel electrophoresis, and has an isoelectric point of 3.75. N-terminal sequencing up to the 33rd residue evidenced a high homology with other snake venom proteinases. The proteinase is of serine-type as indicated by high sensitivity to DFP and shows both Arginine-ester hydrolase and amidase activities on synthetic substrates. Both specific activities were 30-fold higher than the respective activities found in the crude venom. The Km value determined for Arginine-containing substrate BAEE was 3.0 x 10(-4) M and the Km for chromogenic substrate CBS 34-47 0.65 x 10(-4) M. The Vm/Km ratio, however, was two-fold higher for BAEE than for CBS 34-47; the Arginine-Esterase activity of this enzyme is thus slightly higher than its amidase activity.

Pascale Marchot - One of the best experts on this subject based on the ideXlab platform.

  • afaâcytin an αβ fibrinogenase from cerastes cerastes horned viper venom activates purified factor x and induces serotonin release from human blood platelets
    FEBS Journal, 1995
    Co-Authors: Fatirna Larabadjebari, Mariefrance Martineauclaire, Gerard Mauco, Pascale Marchot
    Abstract:

    Afaâcytin, a proteinase with caseinolytic, Arginine-Esterase and amidase activities, was purified from the venom of Cerastes cerastes (horned viper) in two steps by gel filtration through Sephadex G75, then HPLC on carboxymethyl-cellulose. Afaâcytin has an isoelectric point of 6.25. and consists of two sub-units, α and β, which have the same apparent molecular mass (40000) and are indistinguishable in the absence of reduction or/and deglycosylation. Subunit β is constituted of two disulfide-linked polypeptidic chains, β and β′. The respective apparent molecular mass of the chains are 43000 (α), 35500 (β) and 10200 (β') as determined by SDS/PAGE under reducing conditions. Both chains α and β are N-glycosylated. The two chains have the same N-terminal sequence (20 residues) which is similar to those of other proteinases from snake venom. Susceptibility of afaâcytin to diisopropyl fluorophosphate and benzamidine indicates the presence of a serine and an aspartic (or glutamic) acid residues in the catalytic site. Ca2+ appears to be required for structural cohesion of the afaâcytin molecule. Afaâcytin exhibits αβ-fibrinogenase and α-fibrinase properties. It replaces missing factors VIII and IX in deficient plasmas, and activates purified human factor X into factor Xa. It releases serotonin from platelets and directly aggregates human (but not rabbit) blood platelets. Despite its thrombin-like characteristics, however, afaâcytin is not inhibited by plasmatic thrombin inhibitors. The procoagulant properties of afaâcytin therefore have potential clinical applications.

Marie-france Martin-eauclaire - One of the best experts on this subject based on the ideXlab platform.

  • A fibrinogen-clotting serine proteinase from Cerastes cerastes (horned viper) venom with Arginine-Esterase and amidase activities. Purification, characterization and kinetic parameter determination
    Toxicon, 1992
    Co-Authors: Fatima Laraba-djebari, Marie-france Martin-eauclaire, P. Marchot
    Abstract:

    An enzyme displaying proteolytic activity toward the natural substrate casein as well as clotting activity on fibrinogen was purified to homogeneity from Cerastes cerastes (horned viper) venom and characterized. The enzyme is constituted of two identical subunits of mol. wt 48,500 as determined by SDS-polyacrylamide gel electrophoresis, and has an isoelectric point of 3.75. N-terminal sequencing up to the 33rd residue evidenced a high homology with other snake venom proteinases. The proteinase is of serine-type as indicated by high sensitivity to DFP and shows both Arginine-ester hydrolase and amidase activities on synthetic substrates. Both specific activities were 30-fold higher than the respective activities found in the crude venom. The Km value determined for Arginine-containing substrate BAEE was 3.0 x 10(-4) M and the Km for chromogenic substrate CBS 34-47 0.65 x 10(-4) M. The Vm/Km ratio, however, was two-fold higher for BAEE than for CBS 34-47; the Arginine-Esterase activity of this enzyme is thus slightly higher than its amidase activity.

Fatirna Larabadjebari - One of the best experts on this subject based on the ideXlab platform.

  • afaâcytin an αβ fibrinogenase from cerastes cerastes horned viper venom activates purified factor x and induces serotonin release from human blood platelets
    FEBS Journal, 1995
    Co-Authors: Fatirna Larabadjebari, Mariefrance Martineauclaire, Gerard Mauco, Pascale Marchot
    Abstract:

    Afaâcytin, a proteinase with caseinolytic, Arginine-Esterase and amidase activities, was purified from the venom of Cerastes cerastes (horned viper) in two steps by gel filtration through Sephadex G75, then HPLC on carboxymethyl-cellulose. Afaâcytin has an isoelectric point of 6.25. and consists of two sub-units, α and β, which have the same apparent molecular mass (40000) and are indistinguishable in the absence of reduction or/and deglycosylation. Subunit β is constituted of two disulfide-linked polypeptidic chains, β and β′. The respective apparent molecular mass of the chains are 43000 (α), 35500 (β) and 10200 (β') as determined by SDS/PAGE under reducing conditions. Both chains α and β are N-glycosylated. The two chains have the same N-terminal sequence (20 residues) which is similar to those of other proteinases from snake venom. Susceptibility of afaâcytin to diisopropyl fluorophosphate and benzamidine indicates the presence of a serine and an aspartic (or glutamic) acid residues in the catalytic site. Ca2+ appears to be required for structural cohesion of the afaâcytin molecule. Afaâcytin exhibits αβ-fibrinogenase and α-fibrinase properties. It replaces missing factors VIII and IX in deficient plasmas, and activates purified human factor X into factor Xa. It releases serotonin from platelets and directly aggregates human (but not rabbit) blood platelets. Despite its thrombin-like characteristics, however, afaâcytin is not inhibited by plasmatic thrombin inhibitors. The procoagulant properties of afaâcytin therefore have potential clinical applications.