PMID:16128822

Citation	López, V, Alarcón, R, Orellana, MS, Enríquez, P, Uribe, E, Martínez, J and Carvajal, N (2005) Insights into the interaction of human arginase II with substrate and manganese ions by site-directed mutagenesis and kinetic studies. Alteration of substrate specificity by replacement of Asn149 with Asp. FEBS J. 272:4540-8
Abstract	To examine the interaction of human arginase II (EC 3.5.3.1) with substrate and manganese ions, the His120Asn, His145Asn and Asn149Asp mutations were introduced separately. About 53% and 95% of wild-type arginase activity were expressed by fully manganese activated species of the His120Asn and His145Asn variants, respectively. The K(m) for arginine (1.4-1.6 mM) was not altered and the wild-type and mutant enzymes were essentially inactive on agmatine. In contrast, the Asn149Asp mutant expressed almost undetectable activity on arginine, but significant activity on agmatine. The agmatinase activity of Asn149Asp (K(m) = 2.5 +/- 0.2 mM) was markedly resistant to inhibition by arginine. After dialysis against EDTA, the His120Asn variant was totally inactive in the absence of added Mn(2+) and contained < 0.1 Mn(2+).subunit(-1), whereas wild-type and His145Asn enzymes were half active and contained 1.1 +/- 0.1 Mn(2+).subunit(-1) and 1.3 +/- 0.1 Mn(2+).subunit(-1), respectively. Manganese reactivation of metal-free to half active species followed hyperbolic kinetics with K(d) of 1.8 +/- 0.2 x 10(-8) M for the wild-type and His145Asn enzymes and 16.2 +/- 0.5 x 10(-8) m for the His120Asn variant. Upon mutation, the chromatographic behavior, tryptophan fluorescence properties (lambda(max) = 338-339 nm) and sensitivity to thermal inactivation were not altered. The Asn149-->Asp mutation is proposed to generate a conformational change responsible for the altered substrate specificity of arginase II. We also conclude that, in contrast with arginase I, Mn(2+) (A) is the more tightly bound metal ion in arginase II.
Links	PubMed Online version:10.1111/j.1742-4658.2005.04874.x
Keywords	Amino Acid Substitution; Arginase/genetics; Arginase/metabolism; Base Sequence; DNA/genetics; Humans; Kinetics; Manganese/metabolism; Mutagenesis, Site-Directed; Recombinant Proteins/genetics; Recombinant Proteins/metabolism; Substrate Specificity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HUMAN:ARGI2		GO:0004053: arginase activity	ECO:0000315:		F		figure 2	complete CACAO 4514
HUMAN:ARGI2	enables	GO:0004053: arginase activity	ECO:0000315: mutant phenotype evidence used in manual assertion		F		Seeded From UniProt	complete

References

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