Acylation of Bowman-Birk soybean proteinase inhibitor by unsaturated fatty acid derivatives.

A procedure was developed for acylation of Bowman-Birk soybean proteinase inhibitor (BBI) by N-hydroxysuccinimide esters of oleic, linoleic, and alpha-linolenic acids in a dimethyl sulfoxide-dioxane-pyridine mixture. BBI derivatives containing two acylated amino groups were prepared with high yield. The use of the reversible modifier citraconic anhydride in the first stage of synthesis permitted the synthesis of hydrophobized BBI derivatives retaining high antitrypsin and antichymotrypsin activities. It was found that the insertion of two long-chain moieties in the BBI molecule decreases its thermostability.