2v5k
From Proteopedia
Class II aldolase HpcH - magnesium - oxamate complex
Structural highlights
FunctionHPCH_ECOLX Catalyzes the reversible retro-aldol cleavage of 4-hydroxy-2-ketoheptane-1,7-dioate (HKHD) to pyruvate and succinate semialdehyde. Is also able to catalyze the aldol cleavage of 4-hydroxy-2-ketopentanoate and 4-hydroxy-2-ketohexanoate. Is not stereospecific since it can cleave both substrate enantiomers. Also exhibits significant oxaloacetate decarboxylase activity in vitro. In the reverse direction, is able to condense a range of aldehyde acceptors (from two to five carbons in length) with pyruvate or 2-oxobutanoate. Unlike with BphI from Burkholderia xenovorans, the aldol addition reaction lacks stereospecificity, producing a racemic mixture.[1] [2] 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 PubMedMicroorganisms are adept at degrading chemically resistant aromatic compounds. One of the longest and most well characterized aromatic catabolic pathways is the 4-hydroxyphenylacetic acid degradation pathway of Escherichia coli. The final step involves the conversion of 4-hydroxy-2-oxo-heptane-1,7-dioate into pyruvate and succinic semialdehyde. This reaction is catalyzed by 4-hydroxy-2-oxo-heptane-1,7-dioate aldolase (HpcH), a member of the divalent metal ion dependent class II aldolase enzymes that have great biosynthetic potential. We have solved the crystal structure of HpcH in the apo form, and with magnesium and the substrate analogue oxamate bound, to 1.6 A and 2.0 A, respectively. Comparison with similar structures of the homologous 2-dehydro-3-deoxygalactarate aldolase, coupled with site-directed mutagenesis data, implicate histidine 45 and arginine 70 as key catalytic residues. Structure and mechanism of HpcH: a metal ion dependent class II aldolase from the homoprotocatechuate degradation pathway of Escherichia coli.,Rea D, Fulop V, Bugg TD, Roper DI J Mol Biol. 2007 Nov 2;373(4):866-76. Epub 2007 Jun 26. PMID:17881002[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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