1. Nutritional Sciences, Division of Agriculture, Life and Veterinary Sciences, University of Arizona, Tucson, AZ 85721, USA
2. Department of Chemistry and Biochemistry, College of Science, University of Arizona, Tucson, AZ 85721, USA
3. Present Address: Amgen Incorporation, One Amgen Center Drive, Thousand Oaks, CA 91320, USA
4. Department of Biological Sciences, University of Wisconsin-Parkside, Kenosha, WI 53141, USA
5. Present Address: Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA