Navegando por Palavras-chave "plant Kunitz inhibitor"

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    Characterization of a Kunitz trypsin inhibitor with one disulfide bridge purified from Swartzia pickellii
    (Elsevier B.V., 2002-03-01) Cavalcanti, MDM; Oliva, MLV; Fritz, H.; Jochum, M.; Mentele, R.; Sampaio, M.; Coelho, LCBB; Batista, IFC; Sampaio, CAM; Universidade Federal de Pernambuco (UFPE); Univ Pernambuco; Universidade Federal de São Paulo (UNIFESP); Univ Munich
    Swartzia pickellii is a Leguminosae that belongs to the Caesalpinioideae sub-family the Swartzia pickellii Trypsin Inhibitor (SWTI), a serine proteinase inhibitor was isolated from its seeds. SWTI is a single polypeptide chain protein and it's structure has 174 amino acid residues, it homologous to other Kunitz plant inhibitors, however shows some major differences: it contains only one disulfide bridge, instead two which are usually found in plant Kunitz inhibitors, and the SWTI reactive site does not contain the usual Arg or Lys residues at the putative reactive site (position 65). A glycosylation site was detected at Asn38 with 1188 kDa carbohydrate portion. the primary structure micro heterogeneity was found combining the sequence determination and mass spectrometry. Three forms of SWTI were actually defined: two glycosylated forms a 20,204 kDa (Arg 165) and 20,185 kDa (His 165) and one deglycosylated form 19,016 kDa (Arg 165), all of them contain a Met residue at position 130. (C) 2002 Elsevier Science (USA).
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    Kinetic characterization of factor Xa binding using a quenched fluorescent substrate based on the reactive site of factor Xa inhibitor from Bauhinia ungulata seeds
    (Bentham Science Publ Ltd, 2003-07-01) Oliva, Maria Luiza Vilela [UNIFESP]; Andrade, S. A.; Juliano, Maria Aparecida [UNIFESP]; Sallai, Roberto C. [UNIFESP]; Torquato, R. J.; Sampaio, Misako Uemura [UNIFESP]; Pott, V. J.; Sampaio, CAM; Universidade Federal de São Paulo (UNIFESP); Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA)
    The specific Kunitz Bauhinia ungulata factor Xa inhibitor (BuXI) and the Bauhinia variegata trypsin inhibitor (BvTI) blocked the activity of trypsin, chymotrypsin, plasmin, plasma kallikrein and factor XIIa, and factor Xa inhibition was achieved only by BuXI (K-i 14 nM).BuXI and BvTI are highly homologous (70%). the major differences are the methionine residues at BuXI reactive site, which are involved in the inhibition, since the oxidized protein no longer inhibits factor Xa but maintains the trypsin inhibition.Quenched fluorescent substrates based on the reactive site sequence of the inhibitors were synthesized and the kinetic parameters of the hydrolysis were determined using factor Xa and trypsin. the catalytic efficiency k(cat)/K-m 4.3 x 10(7) M(-1)sec(-1) for Abz-VMIAALPRTMFIQ-EDDnp (lead peptide) hydrolysis by factor Xa was 10(4)-fold higher than that of Boc-Ile-Glu-Gly-Arg-AMC, widely used as factor Xa substrate.Lengthening of the substrate changed its susceptibility to factor Xa hydrolysis. Both methionine residues in the substrate influence the binding to factor Xa. Serine replacement of threonine (P-1') decreases the catalytic efficiency by four orders of magnitude. Factor Xa did not hydrolyze the substrate containing the reactive site sequence of BvTI, that inhibits trypsin inhibitor but not factor Xa.Abz-VMIAALPRTMFIQ-EDDnp prolonged both the prothrombin time and the activated partial thromboplastin time, and the other modified substrates used in this experiment altered blood-clotting assays.