1. Protein Engineering Network of Centres of Excellence, University of Alberta, Edmonton, Alberta T6G 2S2, Canada, Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada, Department of Medical Microbiology and Infectious Diseases, University of Alberta, Edmonton, Alberta T6G 2H7, Canada, and Biotechnology Research Institute, the National Research Council of Canada, Montreal, Quebec, H4P 2R2, Canada