Department of Chemistry and Biochemistry, University of California, San Diego La Jolla, CA 92093, USA. bgrant@mccammon.ucsd.edu|Department of Chemistry and Biochemistry, University of California, San Diego La Jolla, CA 92093, USA. bgrant@mccammon.ucsd.edu|Department of Chemistry and Biochemistry, University of California, San Diego La Jolla, CA 92093, USA. bgrant@mccammon.ucsd.edu|Department of Chemistry and Biochemistry, University of California, San Diego La Jolla, CA 92093, USA. bgrant@mccammon.ucsd.edu|Department of Chemistry and Biochemistry, University of California, San Diego La Jolla, CA 92093, USA. bgrant@mccammon.ucsd.edu