Studies on Soybean Trypsin Inhibitors

Abstract

1. A simple method was developed for the preparative purification of large amounts of two soybean trypsin inhibitors, namely the Kunitz-and the 1.9S-inhibitors. 2. These two trypsin inhibitors were characterized in terms of their major chemical and physicochemical properties, and these results were compared with those of soybean trypsin inhibitors isolated by other investigators. The Kunitz-inhibitor was shown to be identical to that isolated by Kunitz and the 1.9S-inhibitor appears to be a new inhibitor. Molecular weight of the 1.9S-inhibitor was determined to be 16,400 and this protein contains more than 19 per cent of cystine and lacks cysteine and glycine. 3. The inhibiting activites of the two inhibitors against several proteinases were investigated.