1. Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182, United States
2. Structural Biochemistry Laboratory, Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182, United States
3. Center for Open Research Resources and Equipment, University of Connecticut, Storrs, Connecticut 06269, United States
4. Department of Molecular and Cell Biology and Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States