[1] Texas A&M Univ, Hlth Sci Ctr, Dept Med Biochem & Genet, College Stn, TX 77843 USA
[2] Texas A&M Univ, Dept Chem, College Stn, TX 77843 USA
[3] Scripps Res Inst, Skaggs Inst Chem Biol, La Jolla, CA 92037 USA
[4] Scripps Res Inst, Dept Chem, La Jolla, CA 92037 USA
[5] Scripps Res Inst, Dept Mol Biol, La Jolla, CA 92037 USA