1. Center for Proteomics and Bioinformatics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
2. Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa 50011
3. Center for Synchrotron Biosciences, Brookhaven National Laboratory, Upton, New York 11973
4. Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461