1ZPE image
Entry Detail
PDB ID:
1ZPE
Keywords:
Title:
Arginase I covalently modified with butylamine at Q19C
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
2005-05-16
Release Date:
2005-12-06
Method Details:
Experimental Method:
Resolution:
1.70 Å
R-Value Free:
0.23
R-Value Work:
0.20
R-Value Observed:
0.20
Space Group:
P 32
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Arginase 1
Mutations:C119A, C168A, C303A, H141A, Q19(BBC)
Chain IDs:A, B, C
Chain Length:314
Number of Molecules:3
Biological Source:Rattus norvegicus
Modified Residue
Compound ID Chain ID Parent Comp ID Details 2D Image
BBC A CYS ?
Ligand Molecules
Primary Citation
Probing the role of the hyper-reactive histidine residue of arginase.
Arch.Biochem.Biophys. 444 15 26 (2005)
PMID: 16266687 DOI: 10.1016/j.abb.2005.09.009

Abstact

Rat liver arginase (arginase I) is potently inactivated by diethyl pyrocarbonate, with a second-order rate constant of 113M(-1)s(-1) for the inactivation process at pH 7.0, 25 degrees C. Partial protection from inactivation is provided by the product of the reaction, l-ornithine, while nearly complete protection is afforded by the inhibitor pair, l-ornithine and borate. The role of H141 has been probed by mutagenesis, chemical modulation, and X-ray diffraction. The hyper-reactivity of H141 towards diethyl pyrocarbonate can be explained by its proximity to E277. A proton shuttling role for H141 is supported by its conformational mobility observed among the known arginase structures. H141 is proposed to serve as an acid/base catalyst, deprotonating the metal-bridging water molecule to generate the metal-bridging hydroxide nucleophile, and by protonating the amino group of the product to facilitate its departure.

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Primary Citation of related structures