ACID‐ AND HEAT‐STABLE TRYPSIN INHIBITORY PEPTIDE FROM THE VISCERA OF JAPANESE COMMON SQUID (TODARODES PACIFICUS)

Trypsin inhibitor was purified from the viscera except for the hepatopancreas of Japanese common squid (Todarodes pacificus) by gel filtration and anion-exchange chromatography. Final inhibitor preparation was homogeneous as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and its molecular weight was estimated to be approximately 6,000 Da. The N-terminal amino acid sequence of the squid trypsin inhibitor was determined as ANEATXVYKGKTYKKGEGF. The purified inhibitor was heat stable up to 150 min at 80C at pH 8.0. The inhibitory activity was also retained at pH 2.0 and 37C for 180 min. The squid trypsin inhibitor was active against walleye pollock trypsin as well as porcine pancreatic trypsin. The squid trypsin inhibitor showed hypoglycemic effect on blood glucose levels of GK rats, a model of type 2 diabetes. PRACTICAL APPLICATIONS In this study, we purified a trypsin inhibitor from the viscera except for hepatopancreas of the Japanese common squid (Todarodes pacificus). The squid trypsin inhibitor was acid and heat stable peptide. So, it was thought that the squid trypsin inhibitor is useful for biochemical regent and medicine of acute inflammation of human pancreas like soybean trypsin inhibitor and bovine aplotinin. Moreover, the squid trypsin inhibitor showed hypoglycemic effect on blood glucose levels of GK rats, a model of type 2 diabetes. Therefore, it may be useful for prevention of diabetes.