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| [[Image:1kar.jpg|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1kar| PDB=1kar | SCENE= }} | | {{STRUCTURE_1kar| PDB=1kar | SCENE= }} |
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| '''L-HISTIDINOL DEHYDROGENASE (HISD) STRUCTURE COMPLEXED WITH HISTAMINE (INHIBITOR), ZINC AND NAD (COFACTOR)'''
| | ===L-HISTIDINOL DEHYDROGENASE (HISD) STRUCTURE COMPLEXED WITH HISTAMINE (INHIBITOR), ZINC AND NAD (COFACTOR)=== |
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| ==Overview==
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| The histidine biosynthetic pathway is an ancient one found in bacteria, archaebacteria, fungi, and plants that converts 5-phosphoribosyl 1-pyrophosphate to l-histidine in 10 enzymatic reactions. This pathway provided a paradigm for the operon, transcriptional regulation of gene expression, and feedback inhibition of a pathway. l-histidinol dehydrogenase (HisD, EC ) catalyzes the last two steps in the biosynthesis of l-histidine: sequential NAD-dependent oxidations of l-histidinol to l-histidinaldehyde and then to l-histidine. HisD functions as a homodimer and requires the presence of one Zn(2+) cation per monomer. We have determined the three-dimensional structure of Escherichia coli HisD in the apo state as well as complexes with substrate, Zn(2+), and NAD(+) (best resolution is 1.7 A). Each monomer is made of four domains, whereas the intertwined dimer possibly results from domain swapping. Two domains display a very similar incomplete Rossmann fold that suggests an ancient event of gene duplication. Residues from both monomers form the active site. Zn(2+) plays a crucial role in substrate binding but is not directly involved in catalysis. The active site residue His-327 participates in acid-base catalysis, whereas Glu-326 activates a water molecule. NAD(+) binds weakly to one of the Rossmann fold domains in a manner different from that previously observed for other proteins having a Rossmann fold. | | The line below this paragraph, {{ABSTRACT_PUBMED_11842181}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 11842181 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_11842181}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Rossman fold]] | | [[Category: Rossman fold]] |
| [[Category: Zinc]] | | [[Category: Zinc]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 22:30:53 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 10:03:03 2008'' |
