1. The Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, Minnesota 55912-3698, Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow, Russian Federation 119333, Department of Biochemistry, Yeungnam University, Kyeongsan, South Korea 712-749, and The Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation 117997