[1] Vanderbilt Univ, Sch Med, Dept Mol Physiol & Biophys, Nashville, TN 37232 USA
[2] Vanderbilt Univ, Sch Med, Dept Microbiol & Immunol, Nashville, TN 37232 USA
[3] Vanderbilt Univ, Sch Med, Mass Spectrometry Res Ctr, Dept Biomed Informat, Nashville, TN 37232 USA
[4] Vanderbilt Univ, Sch Med, Mass Spectrometry Res Ctr, Dept Biochem, Nashville, TN 37232 USA