Purification, inhibitory properties and amino acid sequence of a new serine proteinase inhibitor from white mustard (Sinapis alba L.) seed

[摘要]

A new serine proteinase inhibitor, mustard trypsin inhibitor 2 (MTI-2), has been isolated from white mustard (Sinapis alba L.) seed by affinity chromatography and reverse phase HPLC. The protein inhibits the catalytic activity of bovine β-trypsin and bovine α-chymotrypsin, with dissociation constants (K _d) of 1.6 × 10⁻¹⁰ M and 5.0 × 10⁻⁷ M, respectively, at pH 8.0 and 21°C, the stiochiometry of both proteinase-inhibitor complexes being 1:1. The amino acid sequence of MTI-2, which was determined following S-pyridylethylation, is comprised of 63 residues, corresponding to a molecular weight of about 7 kDa, and shows only extremely limited homology to other serine proteinase inhibitors.

[学科分类] 生物化学/生物物理

[关键词] Serine proteinase inhibitor;Amino acid sequence;Serine proteinase inhibition;White mustard seed;MTI-1;high molecular weight mustard trypsin inhibitor;MTI-2;low molecular weight mustard trypsin inhibitor;TPCK-trypsin;bovine trypsin treated with N-α-tosyl-l-phenylalanine chloromethyl ketone;β-trypsin;bovine β-trypsin;α-chymotrypsin;bovine α-chymotrypsin;BAPNA;N-α-benzoyl-l-arginine p-nitroanilide;ZTyrONp;N-α-carbohenzoxy-l-tyrosine p-nitrophenyl ester;RBTBBI;rice bran trypsin Bowman-Birk inhibitor