A Serine Protease in Soybean Seeds That Acts Specifically on the NativeαSubunit ofβ-Conglycinin

摘要

A proteolytic activity directed against theαsubunit ofβ-conglycinin was detected in resting mature seeds of the soybean Glycine max(L.) Merrill cultivar Keburi. The relationship between pH and activity and the effect of protease inhibitors revealed that the enzyme was a neutral/alkaline serine protease. The proteolysis of theαsubunit ofβ-conglycinin yielded a specific product with a molecular weight of about 47,000, as determined by SDS-PAGE, but the enzyme had no activity against theβsubunit. The amino acid composition, the molecular weight and the amino-terminal amino acid sequence of the proteolytic product revealed that the action of the enzyme on theαsubunit was specific, with cleavage occurring only at the R126-R127 peptide bond of theαsubunit. These characteristics of the protease indicate that the enzyme is a novel protease that has not previously been recognized in soybean