1. Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois, 61801, Department of Bioenergetics, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia, and Helsinki Bioenergetics Group, Department of Medical Chemistry, Institute of Biomedical Sciences, University of Helsinki, Finland