1. Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle, Washington 98195, Protein Engineering Network of Centers of Excellence, University of Alberta, Edmonton, Alberta T6G 2S2, Canada, Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada, and Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada