1. National Food Research Institute, Kannondai 2-1-12, Tsukuba, Ibaraki 305-8642 Japan, Department of Chemistry and Biotechnology, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656, Japan, and Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8573, Japan