1jsr
From Proteopedia
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CRYSTAL STRUCTURE OF ERWINIA CHRYSANTHEMI L-ASPARAGINASE COMPLEXED WITH 6-HYDROXY-L-NORLEUCINE
Overview
The structures of Erwinia chrysanthemi L-asparaginase (ErA) complexed with, the L- and D-stereoisomers of the suicide inhibitor, 6-diazo-5-oxy-norleucine, have been solved using X-ray crystallography and, refined with data extending to 1.7 A. The distances between the Calpha, atoms of the inhibitor molecules and the hydroxyl oxygen atoms of Thr-15, and Tyr-29 (1.20 and 1.60 A, respectively) clearly indicate the presence, of covalent bonds between these moieties, confirming the nucleophilic role, of Thr-15 during the first stage of enzymatic reactions and also, indicating direct involvement of Tyr-29. The factors responsible for, activating Tyr-29 remain unclear, although some structural changes around, Ser-254', Asp-96, and Glu-63, common to both complexes, suggest that those, residues play a function. The role of Glu-289' as the activator of Tyr-29, previously postulated for the closely related Pseudomonas 7A, L-glutaminase-asparaginase, is not confirmed in this study, due to the, lack of interactions between these residues in these complexes and in, holoenzymes. The results reported here are consistent with previous, reports that mutants of Escherichia coli L-asparaginase lacking Glu-289, remain catalytically active and prove the catalytic roles of both Thr-15, and Tyr-29, while still leaving open the question of the exact mechanism, resulting in the unusual chemical properties of these residues.
About this Structure
1JSR is a Single protein structure of sequence from Erwinia chrysanthemi with LDO, 1PE and GOL as ligands. Active as Asparaginase, with EC number 3.5.1.1 Full crystallographic information is available from OCA.
Reference
Do bacterial L-asparaginases utilize a catalytic triad Thr-Tyr-Glu?, Aghaiypour K, Wlodawer A, Lubkowski J, Biochim Biophys Acta. 2001 Dec 17;1550(2):117-28. PMID:11755201
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