1. Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
2. Amersham Pharmacia Biotech, Amersham Labs, White Lion Road, Amersham, Bucks. HP7 9LL, U.K.
3. Dyson Perrins Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QQ, U.K.