4mdh
From Proteopedia
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REFINED CRYSTAL STRUCTURE OF CYTOPLASMIC MALATE DEHYDROGENASE AT 2.5-ANGSTROMS RESOLUTION
Overview
The molecular structure of cytoplasmic malate dehydrogenase from pig heart, has been refined by alternating rounds of restrained least-squares methods, and model readjustment on an interactive graphics system. The resulting, structure contains 333 amino acids in each of the two subunits, 2 NAD, molecules, 471 solvent molecules, and 2 large noncovalently bound, molecules that are assumed to be sulfate ions. The crystallographic study, was done on one entire dimer without symmetry restraints. Analysis of the, relative position of the two subunits shows that the dimer does not obey, exact 2-fold rotational symmetry; instead, the subunits are related by a, 173 degrees rotation. The structure results in a R factor of 16.7% for, diffraction data between 6.0 and 2.5 A, and the rms deviations from ideal, bond lengths and angles are 0.017 A and 2.57 degrees, respectively. The, bound coenzyme in addition to hydrophobic interactions makes numerous, hydrogen bonds that either are directly between NAD and the enzyme or are, with solvent molecules, some of which in turn are hydrogen bonded to the, enzyme. The carboxamide group of NAD is hydrogen bonded to the side chain, of Asn-130 and via a water molecule to the backbone nitrogens of Leu-157, and Asp-158 and to the carbonyl oxygen of Leu-154. Asn-130 is one of the, corner residues in a beta-turn that contains the lone cis peptide bond in, cytoplasmic malate dehydrogenase, situated between Asn-130 and Pro-131., The active site histidine, His-186, is hydrogen bonded from nitrogen ND1, to the carboxylate of Asp-158 and from its nitrogen NE2 to the sulfate ion, bound in the putative substrate binding site. In addition to interacting, with the active site histidine, this sulfate ion is also hydrogen bonded, to the guanidinium group of Arg-161, to the carboxamide group of Asn-140, and to the hydroxyl group of Ser-241. It is speculated that the substrate, malate or oxaloacetate, is bound in the sulfate binding site with the, substrate 1-carboxyl hydrogen bonded to the guanidinium group of Arg-161.
About this Structure
4MDH is a Single protein structure of sequence from Sus scrofa with SO4, ACE and NAD as ligands. This structure superseeds the now removed PDB entries 2MDH and 1MDH. Active as Malate dehydrogenase, with EC number 1.1.1.37 Full crystallographic information is available from OCA.
Reference
Refined crystal structure of cytoplasmic malate dehydrogenase at 2.5-A resolution., Birktoft JJ, Rhodes G, Banaszak LJ, Biochemistry. 1989 Jul 11;28(14):6065-81. PMID:2775751
Page seeded by OCA on Tue Nov 20 19:42:48 2007
