1EYP

CHALCONE ISOMERASE

Summary for 1EYP

• Entry DOI: 10.2210/pdb1eyp/pdb
• Related: 1EYQ
• Descriptor: CHALCONE-FLAVONONE ISOMERASE 1 (2 entities in total)
• Functional Keywords: chalcone isomerase, isomerase
• Biological source: Medicago sativa
• Total number of polymer chains: 2
• Total formula weight: 47702.47

Authors

Jez, J.M.,Bowman, M.E.,Dixon, R.A.,Noel, J.P. (deposition date: 2000-05-08, release date: 2000-09-06, Last modification date: 2024-02-07)

Primary citation

Jez, J.M.,Bowman, M.E.,Dixon, R.A.,Noel, J.P.
Structure and mechanism of the evolutionarily unique plant enzyme chalcone isomerase.
Nat.Struct.Biol., 7:786-791, 2000

PubMed Abstract: 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.

PubMed: 10966651
DOI: 10.1038/79025

Experimental method

X-RAY DIFFRACTION (2.5 Å)