Specific hemoglobin (poly)saccharide recognition

Hemoglobin (Hb) is not a glycoprotein but can easily be glycosylated by a non-enzymatic mechanism. Based on some kinetic particularities, consisting in a faster glycosylation of the amine terminal group of the beta-chain located on the allosteric site, a hypothesis of a recognition center for specific sugars has been advanced. Affinity chromatography materials based on epichlorohydrin crosslinked amylose, agarose and dextran (Sephadex), were used. A specific interaction with the CL-amylose (alpha-1,4-glycosidic links) was found, while for Sephadex (alpha-1,6-glycosidic links), no Hb retention was observed. An affinity retention of hemoglobins (human and bovine) on agarose (a galactose containing carbohydrate) has also been established. Chromatographic studies of Hb competitive elution with several monosaccharides (glucose, fructose, galactose) and disaccharides (saccharose, cellobiose, maltose, lactose) indicated that Hb retained by affinity onto CL-amylose columns, can be eluted only with galactose and lactose; with the other tested saccharides, very poor or no desorption at all, has been observed. These new data suggest: (1) a selective recognition of a limited number of (poly)saccharidic materials; and (2) a different behavior towards various sugars, the best interaction being observed with galactose-containing sugars (lactose). These aspects fit well with the hypothesis of a hemoglobin recognition center for sugars.