Purification, inhibitory properties, amino acid sequence and identification of the reactive site of a new serine proteinase inhibitor from oil-rape (Brassica napus) seed.
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 beta-trypsin and bovine alpha-chymotrypsin with apparent dissociation constants of 3.0 x 10(-10) M and 4.1 x 10(-7) M, at pH 8.0 and 21 degrees 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 P1-P1' reactive site bond has been tentatively identified at position Arg20-Ile21. 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.
Ceciliani
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Istituto di Fisiologia Veterinaria e Biochimica, Università di Milano, Italy.
Bortolotti
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Menegatti
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Ronchi
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Ascenzi
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Palmieri
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D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D001937:Brassica / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D009149:Mustard Plant / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D010946:Plants, Medicinal; D012639:Seeds / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D014361:Trypsin Inhibitors / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*
D010940:Plant Proteins; D014361:Trypsin Inhibitors