Ligand binding characteristics of the major mistletoe lectin

Journal/Book: J. Biol. Chemistry 267 (33), 23722-23727. 1992;

Abstract: Carbohydrate binding specificity of the galactose-specific, major lectinof mistletoe extract (ML-1) was studied by an inhibition assay usingmonosaccharides, monosaccharide derivatives, disaccharides, andcompounds containing multiple galactosyl terminals. The results indicatethat 1) both alpha- and beta-galactosyl residues are recognized equallywell; 2) each of the hydroxyl groups of galactose contributes to varyingdegrees to the binding process, the 4-OH being the most important andthe 6-OH the least important hydroxyl group; 3) disaccharide sequencesof Gal beta 2Gal and Gal beta 3Gal have much higher affinity thangalactose, whereas affinity of all other Gal-disaccharides is onlyslightly better than galactose; 4) macromolecular ligands having 10 ormore terminal galactosyl residues have 500-fold higher affinity thanGal; and 5) a group on ML-1 with pK alpha of 4.8 appears to be involvedin the binding of ligand. Author.

Keyword(s): BINDING-SITES

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