1EYP image
Entry Detail
PDB ID:
1EYP
Keywords:
Title:
CHALCONE ISOMERASE
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2000-05-08
Release Date:
2000-09-06
Method Details:
Experimental Method:
Resolution:
2.50 Å
R-Value Free:
0.28
R-Value Work:
0.24
Space Group:
P 65 2 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:CHALCONE-FLAVONONE ISOMERASE 1
Chain IDs:A, B
Chain Length:222
Number of Molecules:2
Biological Source:Medicago sativa
Primary Citation
Structure and mechanism of the evolutionarily unique plant enzyme chalcone isomerase.
Nat.Struct.Biol. 7 786 791 (2000)
PMID: 10966651 DOI: 10.1038/79025

Abstact

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.

Legend

Protein

Chemical

Disease

Primary Citation of related structures