1eyp
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(New page: 200px<br /><applet load="1eyp" size="450" color="white" frame="true" align="right" spinBox="true" caption="1eyp, resolution 2.5Å" /> '''CHALCONE ISOMERASE'''...)
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Revision as of 12:19, 20 November 2007
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CHALCONE ISOMERASE
Overview
Chalcone isomerase (CHI) catalyzes the intramolecular cyclization of, chalcone synthesized by chalcone synthase (CHS) into (2S)-naringenin, an, essential compound in the biosynthesis of anthocyanin pigments, inducers, of Rhizobium nodulation genes, and antimicrobial phytoalexins. The 1.85 A, resolution crystal structure of alfalfa CHI in complex with, (2S)-naringenin reveals a novel open-faced beta-sandwich fold. Currently, proteins with homologous primary sequences are found only in higher, plants. The topology of the active site cleft defines the stereochemistry, of the cyclization reaction. The structure and mutational analysis suggest, a mechanism in which shape complementarity of the binding cleft locks the, substrate into a constrained conformation that allows the reaction to, proceed with a second-order rate constant approaching the diffusion, controlled limit. This structure raises questions about the evolutionary, history of this structurally unique plant enzyme.
About this Structure
1EYP is a Single protein structure of sequence from Medicago sativa. Active as Chalcone isomerase, with EC number 5.5.1.6 Full crystallographic information is available from OCA.
Reference
Structure and mechanism of the evolutionarily unique plant enzyme chalcone isomerase., Jez JM, Bowman ME, Dixon RA, Noel JP, Nat Struct Biol. 2000 Sep;7(9):786-91. PMID:10966651
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