1eyp
From Proteopedia
CHALCONE ISOMERASE
Structural highlights
Function[CFI1_MEDSA] Catalyzes the intramolecular cyclization of bicyclic chalcones into tricyclic (S)-flavanones. Responsible for the isomerization of 4,2',4',6'-tetrahydroxychalcone (also termed chalcone) into naringenin.[1] [2] [3] 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 PubMedChalcone 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. 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[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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