Primary structure, spectroscopic and inhibitory properties of a two-chain trypsin inhibitor from the seeds of charlock (Sinapis arvensis L), a member of the napin protein family.

A protein with inhibitory activity toward trypsin has been isolated from Sinapis arvensis L (charlock). It has a molecular weight of 15,500 and consists of two chains connected by disulfide bonds. The amino acid sequence was determined and showed that it belongs to the napin family of storage proteins. CD studies showed an alpha-helix content of 12% and a beta-structure of about 50%.