The trypsin and chymotrypsin inhibitors in chick pears (Cicer arietinum L). The relationships among the six isoinhibitors

Multiple trypsin inhibitors from Momordica cochinchinensis seeds, the Chinese drug mubiezhi

Five trypsin inhibitors, with N-terminal sequences demonstrating homology to each other and exhibiting a molecular weight of 5100, 4800, 4400, 4100, and 3900, respectively, were isolated from Momordica cochinchinensis seeds with a protocol involving acid extraction, ion exchange chromatography on SP-Sepharose chromatography, and RP-HPLC on a C18 column. Specific inhibitory activity against trypsin was demonstrated by the trypsin isoinhibitors with Ki values ranging from 5.3 x 10(-8) to 1.8 x 10(-6) M. None of the isoinhibitors could be cleaved by trypsin.

Plant inhibitors of proteolytic enzymes

The presence of inhibitors of proteinases was stated in many species of plants. There are macropeptides of the molecular weight ranging from 3700 to 8000, often bound to carbohydrates. Potential sources of inhibitors of proteinases are legumes, cereals, potatoes and also some fruits. They are characterized by different activity. "Single-headed" inhibitors inhibit one type of proteolytic enzyme, when "double-headed" inhibitors, possessing two independent active sites, can inhibit several types of proteolytic enzymes at the same time. They also differ in the resistance to temperature and change of pH. The role and importance of inhibitors of proteinases is not exactly explained. They are used in the pharmaceutical, baking and beer-industry as well as in the therapy of numerous diseases.