1. Department
of Chemistry, Columbia University, New York, New York 10027, United States
2. Army
Research Laboratory, Aberdeen Proving Ground, Maryland 21005, United States
3. Division
of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden
4. Edgewood
Chemical Biological Center, Aberdeen Proving Ground, Maryland 21010, United States