The amino acid sequence of a cereal Bowman‐Birk type trypsin inhibitor from seeds of Jobs' tears (Coix lachryma‐jobi L.)

Abstract
The major trypsin inhibitor from seeds of Jobs' tears (Coix lachryma‐jobi) was purified by heat treatment, fractional precipitation with (NH4)2SO4, ion‐exchange chromatography on DEAE‐Sepharose, gel‐filtration on Sephadex G‐75 and preparative reverse‐phase HPLC. The complete amino acid sequence was determined by analysis of peptides derived from the reduced and S‐carboxymethylated protein by digestion with trypsin, chymotrypsin and the S. aureus V8 protease. The polypeptide contained 64 amino acids with a high content of cysteine. The sequence exhibited strong homology with a number of Bowman‐Birk inhibitors from legume seeds and similar proteins recently isolated from wheat and rice.