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Structure of 3-isopropylmalate dehydrogenase in complex with the inhibitor and NAD+Structure of 3-isopropylmalate dehydrogenase in complex with the inhibitor and NAD+
Structural highlights
FunctionLEU3_THET8 Catalyzes the oxidation of 3-carboxy-2-hydroxy-4-methylpentanoate (3-isopropylmalate) to 3-carboxy-4-methyl-2-oxopentanoate. The product decarboxylates to 4-methyl-2 oxopentanoate.[HAMAP-Rule:MF_01033] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedIsopropylmalate dehydrogenase (IPMDH) is the third enzyme specific to leucine biosynthesis in microorganisms and plants, and catalyzes the oxidative decarboxylation of (2R,3S)-3-isopropylmalate to alpha-ketoisocaproate using NAD(+) as an oxidizing agent. In this study, a thia-analogue of the substrate was designed and synthesized as an inhibitor for IPMDH. The analogue showed strong competitive inhibitory activity with K(i)=62nM toward IPMDH derived from Thermus thermophilus. Moreover, the crystal structure of T. thermophilus IPMDH in a ternary complex with NAD(+) and the inhibitor has been determined at 2.8A resolution. The inhibitor exists as a decarboxylated product with an enol/enolate form in the active site. The product interacts with Arg 94, Asn 102, Ser 259, Glu 270, and a water molecule hydrogen-bonding with Arg 132. All interactions between the product and the enzyme were observed in the position associated with keto-enol tautomerization. This result implies that the tautomerization step of the thia-analogue during the IPMDH reaction is involved in the inhibition. Crystal structure of 3-isopropylmalate dehydrogenase in complex with NAD(+) and a designed inhibitor.,Nango E, Yamamoto T, Kumasaka T, Eguchi T Bioorg Med Chem. 2009 Nov 15;17(22):7789-94. Epub 2009 Sep 19. PMID:19833522[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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