Crystal structure of Pterocarpus angolensis lectin in complex with glucose, sucrose, and turanose.

Remy Loris, Anne Imberty, Sonia Beeckmans, Edilbert Van Driessche, John S Read, Julie Bouckaert, Henri De Greve, Lieven Buts, Lode Wyns

Index: J. Biol. Chem. 278(18) , 16297-303, (2003)

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Abstract

The crystal structure of the Man/Glc-specific seed lectin from Pterocarpus angolensis was determined in complex with methyl-alpha-d-glucose, sucrose, and turanose. The carbohydrate binding site contains a classic Man/Glc type specificity loop. Its metal binding loop on the other hand is of the long type, different from what is observed in other Man/Glc-specific legume lectins. Glucose binding in the primary binding site is reminiscent of the glucose complexes of concanavalin A and lentil lectin. Sucrose is found to be bound in a conformation similar as seen in the binding site of lentil lectin. A direct hydrogen bond between Ser-137(OG) to Fru(O2) in Pterocarpus angolensis lectin replaces a water-mediated interaction in the equivalent complex of lentil lectin. In the turanose complex, the binding site of the first molecule in the asymmetric unit contains the alphaGlc1-3betaFruf form of furanose while the second molecule contains the alphaGlc1-3betaFrup form in its binding site.