1. Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
2. Department of Biochemistry and the Rosenstiel Basic Medical Sciences Research Institute, Brandeis University, Waltham, Massachusetts 02454, United States
3. Department of Molecular Biology and Computational Biology Unit, Department of Informatics, University of Bergen, 5020 Bergen, Norway
4. Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003, United States