1. Department of Biochemistry, School of Medicine, Chungbuk National University, Cheongju 361-763, South Korea, Microbial Genomics & Applications Center, Korea Research Institute of Bioscience and Biotechnology, Yusong, Daejeon 305-333, South Korea, and Comparative Pharmacokinetics & Microbial Pharmacology, College of Veterinary Medicine, Kyungpook National University, Daegu 702-701, South Korea