2 DUAL TRYPSIN CHYMOTRYPSIN ISO-INHIBITORS PURIFIED FROM FESTUCA-ARUNDINACEA SEED/

Two dual trypsin/chymotrypsin inhibitory proteins (designated iso-inhi bitors I and II) have been purified from dry seeds of Festuca arundina cea (Schreb.) cv. Grasslands Garland using a combination of gel filtra tion and reverse-phase HPLC. SDS-polyacrylamide gel electrophoresis de termined that each protein had a M(r), of ca 10.7 X 10(3) while isoele ctric focusing revealed that the two iso-inhibitors had similar pIs, n ear pH 5.3. Titration of each iso-inhibitor against bovine trypsin and chymotrypsin showed that both proteins were more effective at retardi ng chymotrypsin activity than trypsin activity. For iso-inhibitor I, K -i values were 2.56 x 10(-7) M (for chymotrypsin) and 1.23 X 10(-6) M (for trypsin), and for iso-inhibitor II, K-i values were 3.16 X 10(-7) M (for chymotrypsin) and 1.46 X 10(-6) M (for trypsin). Copyright (C) 1996 Elsevier Science Ltd