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Publication Abstract from PubMed

We determined the crystal structure of EcL-DER to elucidate protein function and substrate specificity. Unlike other asp/glu racemases, EcL-DER has an unbalanced pair of catalytic residues, Thr83/Cys197, at the active site that is crucial for l- to d-unidirectional racemase activity. EcL-DER exhibited racemase activity for both l-glutamate and l-aspartate, but had threefold higher activity for l-glutamate. Based on the structure of the EcL-DER(C197S) mutant in complex with l-glutamate, we determined the binding mode of the l-glutamate substrate in EcL-DER and provide a structural basis for how the protein utilizes l-glutamate as a main substrate. The unidirectionality, despite an equilibrium constant of unity, can be understood in terms of the Haldane relationship.

Structural basis for an atypical active site of an l-aspartate/glutamate-specific racemase from Escherichia coli.,Ahn JW, Chang JH, Kim KJ FEBS Lett. 2015 Dec 21;589(24 Pt B):3842-7. doi: 10.1016/j.febslet.2015.11.003., Epub 2015 Nov 7. PMID:26555188^[1]

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