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'''CRYSTAL STRUCTURE OF A NAD-DEPENDENT D-GLYCERATE DEHYDROGENASE AT 2.4 ANGSTROMS RESOLUTION''' | '''CRYSTAL STRUCTURE OF A NAD-DEPENDENT D-GLYCERATE DEHYDROGENASE AT 2.4 ANGSTROMS RESOLUTION''' | ||
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[[Category: Goldberg, J D.]] | [[Category: Goldberg, J D.]] | ||
[[Category: Yoshida, T.]] | [[Category: Yoshida, T.]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 17:26:41 2008'' | |||
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Revision as of 17:26, 2 May 2008
CRYSTAL STRUCTURE OF A NAD-DEPENDENT D-GLYCERATE DEHYDROGENASE AT 2.4 ANGSTROMS RESOLUTION
OverviewOverview
D-Glycerate dehydrogenase (GDH) catalyzes the NADH-linked reduction of hydroxypyruvate to D-glycerate. GDH is a member of a family of NAD-dependent dehydrogenases that is characterized by a specificity for the D-isomer of the hydroxyacid substrate. The crystal structure of the apoenzyme form of GDH from Hyphomicrobium methylovorum has been determined by the method of isomorphous replacement and refined at 2.4 A resolution using a restrained least-squares method. The crystallographic R-factor is 19.4% for all 24,553 measured reflections between 10.0 and 2.4 A resolution. The GDH molecule is a symmetrical dimer composed of subunits of molecular mass 38,000, and shares significant structural homology with another NAD-dependent enzyme, formate dehydrogenase. The GDH subunit consists of two structurally similar domains that are approximately related to each other by 2-fold symmetry. The domains are separated by a deep cleft that forms the putative NAD and substrate binding sites. One of the domains has been identified as the NAD-binding domain based on its close structural similarity to the NAD-binding domains of other NAD-dependent dehydrogenases. The topology of the second domain is different from that found in the various catalytic domains of other dehydrogenases. A model of a ternary complex of GDH has been built in which putative catalytic residues are identified based on sequence homology between the D-isomer specific dehydrogenases. A structural comparison between GDH and L-lactate dehydrogenase indicates a convergence of active site residues and geometries for these two enzymes. The reactions catalyzed are chemically equivalent but of opposing stereospecificity. A hypothesis is presented to explain how the two enzymes may exploit the same coenzyme stereochemistry and a similar spatial arrangement of catalytic residues to carry out reactions that proceed to opposite enantiomers.
About this StructureAbout this Structure
1GDH is a Single protein structure of sequence from Hyphomicrobium methylovorum. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of a NAD-dependent D-glycerate dehydrogenase at 2.4 A resolution., Goldberg JD, Yoshida T, Brick P, J Mol Biol. 1994 Mar 4;236(4):1123-40. PMID:8120891 Page seeded by OCA on Fri May 2 17:26:41 2008