1. Dong-A University, Hadan 2-dong, Sha-gu, Pusan 604-714, Korea1;
2. Department of Chemistry, University of Massachusetts, Lowell, Massachusetts 018542;
3. Biotechnology Division, U.S. Army Natick RD & E Center, Natick, Massachusetts 017603;
4. Polytechnic University, Brooklyn, New York4; and
5. Department of Chemical & Biological Engineering, Biotechnology Center, Tufts University, Medford, Massachusetts 021555