1rzy
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(New page: 200px<br /><applet load="1rzy" size="450" color="white" frame="true" align="right" spinBox="true" caption="1rzy, resolution 1.80Å" /> '''Crystal structure of...)
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Revision as of 23:52, 20 November 2007
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Crystal structure of rabbit Hint complexed with N-ethylsulfamoyladenosine
Overview
Hint, histidine triad nucleotide-binding protein, is a universally, conserved enzyme that hydrolyzes AMP linked to lysine and, in yeast, functions as a positive regulator of the RNA polymerase II C-terminal, domain kinase, Kin28. To explore the biochemical and structural bases for, the adenosine phosphoramidate hydrolase activity of rabbit Hint, we, synthesized novel substrates linking a p-nitroaniline group to adenylate, (AMP-pNA) and inhibitors that consist of an adenosine group and, 5'-sulfamoyl (AdoOSO(2)NH(2)) or N-ethylsulfamoyl (AdoOSO(2)NHCH(2)CH(3)), group. AMP-pNA is a suitable substrate for Hint that allowed, characterization of the inhibitors; titration of each inhibitor into, AMP-pNA assays revealed their K(i) values. The N-ethylsulfamoyl derivative, has a 13-fold binding advantage over the sulfamoyl adenosine. The 1.8-A, cocrystal structure of rabbit Hint with N-ethylsulfamoyl adenosine, revealed a binding site for the ethyl group against Trp-123, a residue, that reaches across the Hint dimer interface to interact with the alkyl, portion of the inhibitor and, presumably, the alkyl portion of a lysyl, substrate. Ser-107 is positioned to donate a hydrogen bond to the leaving, group nitrogen. Consistent with a role in acid-base catalysis, the Hint, S107A mutant protein displayed depressed catalytic activity.
About this Structure
1RZY is a Single protein structure of sequence from Oryctolagus cuniculus with 5AS as ligand. Full crystallographic information is available from OCA.
Reference
Biochemical, crystallographic, and mutagenic characterization of hint, the AMP-lysine hydrolase, with novel substrates and inhibitors., Krakowiak A, Pace HC, Blackburn GM, Adams M, Mekhalfia A, Kaczmarek R, Baraniak J, Stec WJ, Brenner C, J Biol Chem. 2004 Apr 30;279(18):18711-6. Epub 2004 Feb 24. PMID:14982931
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