[1] Univ Tennessee, Dept Biochem & Cellular & Mol Biol, Knoxville, TN 37996 USA
[2] Catholic Univ Louvain, Unite Chim Interfaces, B-1348 Louvain, Belgium
[3] Oak Ridge Natl Lab, Biosci Div, Biol & Nanoscale Syst Grp, Oak Ridge, TN 37831 USA
[4] Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA