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1hzj
From Proteopedia
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==Overview== | ==Overview== | ||
| - | UDP-galactose 4-epimerase catalyzes the interconversion of UDP-galactose | + | UDP-galactose 4-epimerase catalyzes the interconversion of UDP-galactose and UDP-glucose during normal galactose metabolism. One of the key structural features in the proposed reaction mechanism for the enzyme is the rotation of a 4'-ketopyranose intermediate within the active site pocket. Recently, the three-dimensional structure of the human enzyme with bound NADH and UDP-glucose was determined. Unlike that observed for the protein isolated from Escherichia coli, the human enzyme can also turn over UDP-GlcNAc to UDP-GalNAc and vice versa. Here we describe the three-dimensional structure of human epimerase complexed with NADH and UDP-GlcNAc. To accommodate the additional N-acetyl group at the C2 position of the sugar, the side chain of Asn-207 rotates toward the interior of the protein and interacts with Glu-199. Strikingly, in the human enzyme, the structural equivalent of Tyr-299 in the E. coli protein is replaced with a cysteine residue (Cys-307) and the active site volume for the human protein is calculated to be approximately 15% larger than that observed for the bacterial epimerase. This combination of a larger active site cavity and amino acid residue replacement most likely accounts for the inability of the E. coli enzyme to interconvert UDP-GlcNAc and UDP-GalNAc. |
==Disease== | ==Disease== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: UDP-glucose 4-epimerase]] | [[Category: UDP-glucose 4-epimerase]] | ||
| - | [[Category: Fridovich-Keil, J | + | [[Category: Fridovich-Keil, J L.]] |
| - | [[Category: Holden, H | + | [[Category: Holden, H M.]] |
| - | [[Category: Thoden, J | + | [[Category: Thoden, J B.]] |
| - | [[Category: Wohlers, T | + | [[Category: Wohlers, T M.]] |
[[Category: CL]] | [[Category: CL]] | ||
[[Category: MG]] | [[Category: MG]] | ||
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[[Category: short-chain dehydrogenase]] | [[Category: short-chain dehydrogenase]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:06:23 2008'' |
Revision as of 11:06, 21 February 2008
|
HUMAN UDP-GALACTOSE 4-EPIMERASE: ACCOMMODATION OF UDP-N-ACETYLGLUCOSAMINE WITHIN THE ACTIVE SITE
Contents |
Overview
UDP-galactose 4-epimerase catalyzes the interconversion of UDP-galactose and UDP-glucose during normal galactose metabolism. One of the key structural features in the proposed reaction mechanism for the enzyme is the rotation of a 4'-ketopyranose intermediate within the active site pocket. Recently, the three-dimensional structure of the human enzyme with bound NADH and UDP-glucose was determined. Unlike that observed for the protein isolated from Escherichia coli, the human enzyme can also turn over UDP-GlcNAc to UDP-GalNAc and vice versa. Here we describe the three-dimensional structure of human epimerase complexed with NADH and UDP-GlcNAc. To accommodate the additional N-acetyl group at the C2 position of the sugar, the side chain of Asn-207 rotates toward the interior of the protein and interacts with Glu-199. Strikingly, in the human enzyme, the structural equivalent of Tyr-299 in the E. coli protein is replaced with a cysteine residue (Cys-307) and the active site volume for the human protein is calculated to be approximately 15% larger than that observed for the bacterial epimerase. This combination of a larger active site cavity and amino acid residue replacement most likely accounts for the inability of the E. coli enzyme to interconvert UDP-GlcNAc and UDP-GalNAc.
Disease
Known disease associated with this structure: Galactose epimerase deficiency OMIM:[606953]
About this Structure
1HZJ is a Single protein structure of sequence from Homo sapiens with , , and as ligands. Active as UDP-glucose 4-epimerase, with EC number 5.1.3.2 Full crystallographic information is available from OCA.
Reference
Human UDP-galactose 4-epimerase. Accommodation of UDP-N-acetylglucosamine within the active site., Thoden JB, Wohlers TM, Fridovich-Keil JL, Holden HM, J Biol Chem. 2001 May 4;276(18):15131-6. Epub 2001 Jan 26. PMID:11279032
Page seeded by OCA on Thu Feb 21 13:06:23 2008
