title: Primary structure and reactive site of a novel wheat proteinase inhibitor of subtilisin and chymotrypsin.
abstract: The proteinase inhibitor WSCI, active in inhibiting bacterial subtilisin and a number of animal chymotrypsins, was purified from endosperm of exaploid wheat (Triticum aestivum, c.v. San Pastore) by ion exchange chromatography and its complete amino acid sequence was established by automated Edman degradation. WSCI consists of a single polypeptide chain of 72 amino acid residues, has a molecular mass of 8126.3 Da and a pl of 5.8. The inhibition constants (Ki) for Bacillus licheniformis subtilisin and bovine pancreatic alpha-chymotrypsin are 3.92 x 10(-9) M and 7.24 x 10(-9) M, respectively. The inhibitor contains one methionine and of tryptophan residue and has a high content of essential amino acids (41 over a total of 72 residues), but no cysteines. The primary structure of WSCI shows high similarity with barley subtilisin-chymotrypsin isoinhibitors of the Cl-2 type and with maize subtilisinchymotrypsin inhibitor MPI. Significant degrees of similarity were also found between sequences of WSCI and of other members of the potato inhibitor I family of the serine proteinase inhibitors. The wheat inhibitor WSCI has a single reactive site (the peptide bond between methionyl-48 and glutamyl-49 residues) as identified by affinity chromatography and sequence analysis.
authors.affiliation: Dipartimento di Agrobiologia e Agrochimica, Università della Tuscia, I-01100 Viterbo, Italy.
authors.forename: Elia
authors.initials: E
authors.lastname: Poerio
authors.forename: Simone
authors.initials: S
authors.lastname: Di Gennaro
authors.forename: Antimo
authors.initials: A
authors.lastname: Di Maro
authors.forename: Francesca
authors.initials: F
authors.lastname: Farisei
authors.forename: Pasquale
authors.initials: P
authors.lastname: Ferranti
authors.forename: Augusto
authors.initials: A
authors.lastname: Parente
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001407:Bacillus / Q000145:classification / Q000201:enzymology; D001665:Binding Sites; D002417:Cattle; D002846:Chromatography, Affinity; D002918:Chymotrypsin / Q000037:antagonists & inhibitors*; D008969:Molecular Sequence Data; D017421:Sequence Analysis / Q000379:methods; D017386:Sequence Homology, Amino Acid; D015842:Serine Proteinase Inhibitors / Q000235:genetics* / Q000302:isolation & purification; D020860:Subtilisin / Q000037:antagonists & inhibitors*; D014908:Triticum / Q000737:chemistry*
chemical_list: D015842:Serine Proteinase Inhibitors; D002918:Chymotrypsin; D020860:Subtilisin