1bjp
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(New page: 200px<br /><applet load="1bjp" size="450" color="white" frame="true" align="right" spinBox="true" caption="1bjp, resolution 2.40Å" /> '''CRYSTAL STRUCTURE OF...)
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Revision as of 09:35, 20 November 2007
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CRYSTAL STRUCTURE OF 4-OXALOCROTONATE TAUTOMERASE INACTIVATED BY 2-OXO-3-PENTYNOATE AT 2.4 ANGSTROMS RESOLUTION
Overview
The crystal structure of 4-oxalocrotonate tautomerase (4-OT) inactivated, by the active site-directed irreversible inhibitor 2-oxo-3-pentynoate, (2-OP) has been determined to 2.4 A resolution. The structure of the, enzyme covalently modified at Pro-1 by the resulting 2-oxo-3-pentenoate, adduct is nearly superimposable on that of the free enzyme and confirms, that the active site is located in a hydrophobic region surrounding Pro-1., Both structures can be described as a trimer of dimers where each dimer, consists of a four-stranded beta-sheet with two antiparallel alpha-helices, on one side. Examination of the structure also reveals noncovalent, interactions between the adduct and two residues in the active site. The, epsilon and eta nitrogens of the guanidinium side chain of Arg-39" from a, neighboring dimer interact respectively with the C-2 carbonyl oxygen and, one C-1 carboxylate oxygen of the adduct while the side chain of Arg-61', from the same dimer as the modified Pro-1 interacts with the C-1, carboxylate group in a bidentate fashion. An additional interaction to the, 2-oxo group of the adduct is provided by one of the two ordered water, molecules within the active site region. These interactions coupled with, the observation that 2-oxo-3-butynoate is a more potent irreversible, inhibitor of 4-oxalocrotonate tautomerase than is 2-OP suggest that, Arg-39" and the ordered water molecule polarize the carbonyl group of 2-OP, which facilitates a Michael reaction between Pro-1 and the acetylene, compound. On the basis of the crystal structure, a mechanism for the, enzyme-catalyzed reaction is proposed.
About this Structure
1BJP is a Single protein structure of sequence from Pseudomonas putida with OXP as ligand. Full crystallographic information is available from OCA.
Reference
Crystal structure of 4-oxalocrotonate tautomerase inactivated by 2-oxo-3-pentynoate at 2.4 A resolution: analysis and implications for the mechanism of inactivation and catalysis., Taylor AB, Czerwinski RM, Johnson WH Jr, Whitman CP, Hackert ML, Biochemistry. 1998 Oct 20;37(42):14692-700. PMID:9778344
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