1. Structural Biochemistry Unit, NIDCR, NIH, Bethesda, MD 20892, USA.
2. Bioinformatics and Computational Biosciences Branch, OCICB, NIAID, NIH, Bethesda, MD 20892, USA.
3. MICaB Program, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
4. Section on Biological Chemistry, NIDCR, NIH, Bethesda, MD 20892, USA.