Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America.|Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America.|Department of Natural Sciences, New College of Florida, Sarasota, Florida, United States of America.|Department of Physics and Astronomy, Earlham College, Richmond, Indiana, United States of America.|Department of Chemistry, University of South Florida, Tampa, Florida, United States of America.|Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America.