1. National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan, Faculty of Engineering, Aomori University, 2-3-1 Kobata, Aomori 030-0943, Japan, Peptide Institute Inc., Protein Research Foundation, Minoh, Osaka 562-8686, Japan, and Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan