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Publication Abstract from PubMed

The crystal structure of Escherichia coli ketopantoate reductase in complex with 2'-monophosphoadenosine 5'-diphosphoribose, a fragment of NADP+ that lacks the nicotinamide ring, is reported. The ligand is bound at the enzyme active site in the opposite orientation to that observed for NADP+, with the adenine ring occupying the lipophilic nicotinamide pocket. Isothermal titration calorimetry with R31A and N98A mutants of the enzyme is used to show that the unusual ;reversed binding mode' observed in the crystal is triggered by changes in the protonation of binding groups at low pH. This research has important implications for fragment-based approaches to drug design, namely that the crystallization conditions and the chemical modification of ligands can have unexpected effects on the binding modes.

pH-tuneable binding of 2'-phospho-ADP-ribose to ketopantoate reductase: a structural and calorimetric study.,Ciulli A, Lobley CM, Tuck KL, Smith AG, Blundell TL, Abell C Acta Crystallogr D Biol Crystallogr. 2007 Feb;63(Pt 2):171-8. Epub 2007, Jan 16. PMID:17242510^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.