BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS Pages]214-I 22] THE SOLUTION CONFORMATION OF THE Le ~ GROUP

The solution conformation of the non-reducing terminal Gal~l--4(Fucal-~3)GIcNAc (Lewis X or Le =) group in the oligosaccharide Lacto-N-fucopentaose (LNFP) III has been determined by high resolution t H NMR spectroscopy and seml-empirical quantum mechanical calculations. The two methods give the same single conformer for the Le ~ group showing close packing of the Gal and Fuc rings. The metal binding properties and homotypic oligomer formation of LNFP Ill have also been investigated by NMR spec-troscopy. No evidence for metal binding or high-affinity homotypic oligomer formation has been found. ® i991 Academic Pr~s, ~o. Cell surface carbohydrates are known to be involved in specific cell-cell interactions via carbohydrate-lectin complexes [1]. In particular, interest has focused on the family of oligosaccharides containing one or more non-reducing terminal Le = groups (fig la) or substituted Le = groups (especially sialyI-Le:) [2,3]. Differential expression of cell surface Le ~ and sialyI-Le ~ determinants has also been observed during different stages of cellular development, differentiation and maturation [4]. More recently, carbohydrates, and particularly oligosaccharides containing the non