1. Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, Columbia, South Carolina 29208, Department of Biochemistry and Molecular Biology, University of Southern California, 1333 San Pablo Street, MCA 51A, Los Angeles, California 90089, and Graduate School of Integrated Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan