1. Department
of Biochemistry, ‡Institute for Genomic Biology and §Center for Biophysics
and Computational Biology, University of Illinois at Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States and
2. Departments of Chemical and Biological
Engineering, ⊥Molecular Biology,
and #Chemistry Princeton University, Princeton, New Jersey 08544, United States