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| {{STRUCTURE_1a80| PDB=1a80 | SCENE= }} | | {{STRUCTURE_1a80| PDB=1a80 | SCENE= }} |
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| '''NATIVE 2,5-DIKETO-D-GLUCONIC ACID REDUCTASE A FROM CORYNBACTERIUM SP. COMPLEXED WITH NADPH'''
| | ===NATIVE 2,5-DIKETO-D-GLUCONIC ACID REDUCTASE A FROM CORYNBACTERIUM SP. COMPLEXED WITH NADPH=== |
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| ==Overview==
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| The three-dimensional structure of Corynebacterium 2, 5-diketo-D-gluconic acid reductase A (2,5-DKGR A; EC 1.1.1.-), in complex with cofactor NADPH, has been solved by using x-ray crystallographic data to 2.1-A resolution. This enzyme catalyzes stereospecific reduction of 2,5-diketo-D-gluconate (2,5-DKG) to 2-keto-L-gulonate. Thus the three-dimensional structure has now been solved for a prokaryotic example of the aldo-keto reductase superfamily. The details of the binding of the NADPH cofactor help to explain why 2,5-DKGR exhibits lower binding affinity for cofactor than the related human aldose reductase does. Furthermore, changes in the local loop structure near the cofactor suggest that 2,5-DKGR will not exhibit the biphasic cofactor binding characteristics observed in aldose reductase. Although the crystal structure does not include substrate, the two ordered water molecules present within the substrate-binding pocket are postulated to provide positional landmarks for the substrate 5-keto and 4-hydroxyl groups. The structural basis for several previously described active-site mutants of 2,5-DKGR A is also proposed. Recent research efforts have described a novel approach to the synthesis of L-ascorbate (vitamin C) by using a genetically engineered microorganism that is capable of synthesizing 2,5-DKG from glucose and subsequently is transformed with the gene for 2,5-DKGR. These modifications create a microorganism capable of direct production of 2-keto-L-gulonate from D-glucose, and the gulonate can subsequently be converted into vitamin C. In economic terms, vitamin C is the single most important specialty chemical manufactured in the world. Understanding the structural determinants of specificity, catalysis, and stability for 2,5-DKGR A is of substantial commercial interest.
| | The line below this paragraph, {{ABSTRACT_PUBMED_9618487}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 9618487 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_9618487}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Commercial vitamin c synthesis]] | | [[Category: Commercial vitamin c synthesis]] |
| [[Category: Oxidoreductase]] | | [[Category: Oxidoreductase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 09:57:10 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 16:20:22 2008'' |
