Malate dehydrogenase

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Line 60: Line 60:
[[1wze]] – TfMDH (mutant)+NAD – ''Thermus flavus''<br />
[[1wze]] – TfMDH (mutant)+NAD – ''Thermus flavus''<br />
[[1wzi]] - TfMDH (mutant)+NDP<br />
[[1wzi]] - TfMDH (mutant)+NDP<br />
-
[[1bdm]] - TfMDH (mutant)+beta-6-hydroxy-1,4,5,6-tetrhydronicotinamide adenine dinucleotide<br />
+
[[1bdm]] - TfMDH (mutant)+beta-6-hydroxy-1,4,5,6-tetrahydronicotinamide adenine dinucleotide<br />
[[1bmd]] – TfMDH+NAD<br />
[[1bmd]] – TfMDH+NAD<br />
[[1y7t]] – TtMDH+NADPH – ''Thermus thermophilus''<br />
[[1y7t]] – TtMDH+NADPH – ''Thermus thermophilus''<br />

Revision as of 10:16, 7 February 2013

Crystal Structure of Malate Dehydrogenase 2x0i
Crystal Structure of Malate Dehydrogenase 2x0i

Template:STRUCTURE 2j5r










Malate Dehydrogenase (MDH)(PDB entry 2x0i) is most known for its role in the metabolic pathway of the tricarboxylic acid cycle, also know as the Kreb's Cycle, which is critical to cellular respiration in cells [1]; however, the enzyme is also in many other metabolic pathways such as glyoxylate bypass, amino acid synthesis, glucogenesis, and oxidation/reduction balance [1]. It is classified as an oxidoreductase[2]. Malate Dehydrogenase has been extensively studied due to its many isozymes [2]. The enzyme exists in two places inside a cell: the mitochondria and cytoplasm. In the mitochondria, the enzyme catalyzes the reaction of malate to oxaloacetate; however, in the cytoplasm, the enzyme catalyzes oxaloacetate to malate to allow transport [3]. This conversion is an essential catalytic step in each different metabolic mechanism. The enzyme malate dehydrogenase is composed of either a dimer or tetramer depending on the location of the enzyme and the organism it is located in [4]. During catalysis, the enzyme subunits are non-cooperative between active sites. The mitochondrial MDH is complexly, allosterically controlled by citrate, but no other known metabolic regulation mechanisms have been discovered. Further, the exact mechanism of regulation has yet to be discovered [5]. Kinetically, the pH of optimization is 7.6 for oxaloacetate conversion and 9.6 for malate conversion. The reported K(m) value for malate conversion is 215 uM and the V(max) value is 87.8 uM/min [6].

Malate dehydrogenase monomer complex with NADH, sulfate and Na+ ion, 2xi0

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