Banana lectin is unique in its recognition of the reducing unit of 3-O-{szligbeta}-glucosyl/mannosyl disaccharides: a calorimetric study

• Published in: Glycobiology (Oxford) Vol. 15; no. 10; pp. 1043 - 1050
• Main Authors: Winter, Harry C, Oscarson, Stefan, Slättegård, Rikard, Tian, Maozhong, Goldstein, Irwin J
• Format: Journal Article
• Language: English
• Published: 2005
• ISSN: 0959-6658; 1460-2423

The binding of banana lectin (BanLec) to laminaribiose (Glc{szligbeta}1,3Glc) and a series of novel synthetic analogues was measured by titration calorimetry to assess the contribution of the hydroxyl groups of the reducing glycosyl moiety and its 3-O-{szligbeta}-substituent to binding. Key areas of interaction involved the 1, 2, and 6 positions of the reducing-terminal hexose unit. The [alpha]-anomeric configuration of the reducing hexose was strongly favored over the {szligbeta}-anomer. The 2-hydroxyl in the axial position (mannose) also enhanced binding, whereas the 6-hydroxymethyl group was essential, because xylopyranose in the reducing position was inactive. The 3-O-{szligbeta}-glucosyl unit of methyl [alpha]-laminaribioside could be replaced by any of its monodeoxy derivatives. However, the 49-deoxy derivative or axial hydroxy (galactosyl) substitution was somewhat detrimental to binding. 3-O-substitution with the (S)tetrahydropyranyl ring or a benzyl group had similar effect as 49-deoxyglucosyl substitution. Surprisingly, p-nitrobenzyl or {szligbeta}-xylosyl 3-O-substitution greatly enhanced binding of the reducing glucosyl or mannosyl derivative. Chemical syntheses of a number of novel disaccharides and analogues prepared for this study are described.