[1] Texas A&M Univ Syst Hlth Sci Ctr, Coll Med, Dept Med Biochem & Genet, College Stn, TX 77843 USA
[2] Univ Oklahoma, Hlth Sci Ctr, Dept Microbiol & Immunol, Oklahoma City, OK 73190 USA
[3] Texas A&M Univ, Dept Chem, College Stn, TX 77843 USA
[4] Texas A&M Univ, Dept Biochem & Biophys, College Stn, TX 77843 USA