1eyp
From Proteopedia
(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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| - | [[Image:1eyp.jpg|left|200px]]<br /><applet load="1eyp" size=" | + | [[Image:1eyp.jpg|left|200px]]<br /><applet load="1eyp" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1eyp, resolution 2.5Å" /> | caption="1eyp, resolution 2.5Å" /> | ||
'''CHALCONE ISOMERASE'''<br /> | '''CHALCONE ISOMERASE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Chalcone isomerase (CHI) catalyzes the intramolecular cyclization of | + | 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== | ==About this Structure== | ||
| - | 1EYP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Medicago_sativa Medicago sativa]. Active as [http://en.wikipedia.org/wiki/Chalcone_isomerase Chalcone isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.5.1.6 5.5.1.6] Full crystallographic information is available from [http:// | + | 1EYP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Medicago_sativa Medicago sativa]. Active as [http://en.wikipedia.org/wiki/Chalcone_isomerase Chalcone isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.5.1.6 5.5.1.6] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1EYP OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Medicago sativa]] | [[Category: Medicago sativa]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Bowman, M | + | [[Category: Bowman, M E.]] |
| - | [[Category: Dixon, R | + | [[Category: Dixon, R A.]] |
| - | [[Category: Jez, J | + | [[Category: Jez, J M.]] |
| - | [[Category: Noel, J | + | [[Category: Noel, J P.]] |
[[Category: chalcone isomerase]] | [[Category: chalcone isomerase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:32:58 2008'' |
Revision as of 10:33, 21 February 2008
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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
Page seeded by OCA on Thu Feb 21 12:32:58 2008
