1p8q
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Structural and Functional Importance of First-Shell Metal Ligands in the Binuclear Cluster of Arginase I.
OverviewOverview
Arginase is a binuclear manganese metalloenzyme that hydrolyzes l-arginine, to form l-ornithine and urea. The three-dimensional structures of D128E, D128N, D232A, D232C, D234E, H101N, and H101E arginases I have been, determined by X-ray crystallographic methods to elucidate the roles of the, first-shell metal ligands in the stability and catalytic activity of the, enzyme. This work represents the first structure-based dissection of the, binuclear manganese cluster using site-directed mutagenesis and X-ray, crystallography. Substitution of the metal ligands compromises the, catalytic activity of the enzyme, either by the loss or disruption of the, metal cluster or the nucleophilic metal-bridging hydroxide ion. However, the substitution of the metal ligands or the reduction of Mn(2+)(A) or, Mn(2+)(B) occupancy does not compromise enzyme-substrate affinity as, reflected by K(M), which remains relatively invariant across this series, of arginase variants. This implicates a nonmetal binding site for, substrate l-arginine in the precatalytic Michaelis complex, as proposed, based on analysis of the native enzyme structure (Kanyo, Z. F., Scolnick, L. R., Ash, D. E., and Christianson, D. W. (1996) Nature 383, 554-557).
About this StructureAbout this Structure
1P8Q is a Single protein structure of sequence from Rattus norvegicus with MN and GOL as ligands. Active as Arginase, with EC number 3.5.3.1 Full crystallographic information is available from OCA.
ReferenceReference
Structural and functional importance of first-shell metal ligands in the binuclear manganese cluster of arginase I., Cama E, Emig FA, Ash DE, Christianson DW, Biochemistry. 2003 Jul 1;42(25):7748-58. PMID:12820884
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