1. Computational Biology
Center, IBM Thomas J. Watson Research Center, Yorktown Heights,
New York 10598, United States
2. Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712,
United States
3. Department of Chemistry and
Chemical Biology, Harvard University, Cambridge,
Massachusetts 02138, United States
4. Department
of Chemistry, Columbia University, New
York, New York 10027, United
States