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Purification, inhibitory properties, amino acid sequence and identification of the reactive site of a new serine proteinase inhibitor from oil‐rape (itBrassica napus) seed
Author(s) -
Ceciliani Fabrizio,
Bortolotti Fabrizio,
Menegatti Enea,
Ronchi Severino,
Ascenzi Paolo,
Palmieri Sandro
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)80505-9
Subject(s) - serine , biochemistry , proteinase 3 , trypsin , serine proteinase inhibitors , trypsin inhibitor , chemistry , rapeseed , chymotrypsin , amino acid , kunitz sti protease inhibitor , enzyme , biology , serine protease , protease , myeloperoxidase , food science , immunology , inflammation
A new serine proteinase inhibitor, rapeseed trypsin inhibitor (RTI), has been isolated from rapeseed ( Brassica napus var. oleifera) seed. The protein inhibits the catalytic activity of bovine β‐trypsin and bovine α‐chymotrypsin with apparent dissociation constants of 3.0 × 10 −10 M and 4.1 × 10 −7 M, at pH 8.0 and 21°C, respectively. The stoichiometry of both proteinase‐inhibitor complexes is 1:1. The amino acid sequence of RTI consists of 60 amino acid residues, corresponding to an M r , of about 6.7 kDa. The p 1 ‐p i , reactive site bond has been tentatively identified at position Arg 20 ‐Ile 21 . RTI shows no similarity to other serine proteinase inhibitors except the low molecular weight mustard trypsin inhibitor (MTI‐2). RTI and MTI‐2 could be members of a new class of plant serine proteinase inhibitors.