Purification and partial characterization of trypsin/ chymotrypsin inhibitors from cabbage foliage

Proteinase inhibitors from cabbage foliage (Brassica oleracea) had trypsin and chymotrypsin inhibitory activity that was relatively stable over a broad range of temperatures (0–100°) and pH values (4.5–7.5). The six proteinase inhibitors that were purified by affinity chromatography had Mrs that ranged from 9000 to 25 000, and isoelectric points that ranged from 4.5 to 5.0. Separation of these affinity-purified proteins by reverse phase HPLC resulted in 14 unique protein species with trypsin and chymotrypsin inhibitory activity. Based on similarities in the amino acid content, the HPLC-purified inhibitors were arranged into four groups.