Isolation and primary structure of a methionine- and cystine-rich seed protein of Cannabis sativa

A 10-kDa protein was isolated from resting seeds of hemp (Cannabis sativa) by buffer extraction, gel filtration, ion-exchange chromatography, and reversed-phase high-pressure liquid chromatography. The protein did not inhibit bovine trypsin. It consisted of subunits composed of 27 and 61 residues and was held together by two disulfide bonds. The complete amino acid sequence was identified by protein analysis, and had 20 mole% of amino acids containing sulfur. The protein was most similar to a methionine-rich protein of Brazil nut (Bertholletia excelsa) and to Mabinlin IV, a sweetness-inducing protein of Capparis masaikai. The high methionine content and the absence of trypsin inhibitory activity suggested that the seed protein can be used to improve the nutritional quality of plant foodstuffs.