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| | {{STRUCTURE_2hzp| PDB=2hzp | SCENE= }} | | {{STRUCTURE_2hzp| PDB=2hzp | SCENE= }} |
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| - | '''Crystal Structure of Homo Sapiens Kynureninase'''
| + | ===Crystal Structure of Homo Sapiens Kynureninase=== |
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| - | ==Overview==
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| - | Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_17300176}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 17300176 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_17300176}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Quinolinic acid]] | | [[Category: Quinolinic acid]] |
| | [[Category: Vitamin b6]] | | [[Category: Vitamin b6]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 06:54:27 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 06:41:19 2008'' |
Revision as of 03:41, 28 July 2008
Template:STRUCTURE 2hzp
Crystal Structure of Homo Sapiens Kynureninase
Template:ABSTRACT PUBMED 17300176
About this Structure
2HZP is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Crystal structure of Homo sapiens kynureninase., Lima S, Khristoforov R, Momany C, Phillips RS, Biochemistry. 2007 Mar 13;46(10):2735-44. Epub 2007 Feb 15. PMID:17300176
Page seeded by OCA on Mon Jul 28 06:41:19 2008
