1. National Institute for Advanced Interdisciplinary Research, Agency of Industrial Science and Technology, 1-1-4 Higashi, Tsukuba, Ibaraki 305, Japan; Laboratory of Biophysical Chemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan; and Institute of Electrical Sciences, Hokkaido University, Sapporo 060-0812