[1] Mayo Clin, Dept Biochem & Mol Biol, Guggenheim Coll Med 1311B, Rochester, MN 55905 USA
[2] Univ Missouri, Dept Chem, Columbia, MO 65211 USA
[3] Univ Missouri, Univ Missouri Res Reactor, Columbia, MO 65211 USA
[4] Mayo Clin, Coll Med, Guggenheim Coll Med 1311B, Ctr Canc, Rochester, MN 55905 USA