Publication Abstract from PubMed
Arginase is a thermostable (Tm = 75 degrees C) binuclear manganese metalloenzyme which hydrolyzes l-arginine to form l-ornithine and urea. The three-dimensional structures of native metal-depleted arginase, metal-loaded H101N arginase, and metal-depleted H101N arginase have been determined by X-ray crystallographic methods to probe the roles of the manganese ion in site A (Mn2+A) and its ligand H101 in catalysis and thermostability. We correlate these structures with thermal stability and catalytic activity measurements reported here and elsewhere [Cavalli, R. C., Burke, C. J., Kawamoto, S., Soprano, D. R., and Ash, D. E. (1994) Biochemistry 33, 10652-10657]. We conclude that the substitution of a wild-type histidine ligand to Mn2+A compromises metal binding, which in turn compromises protein thermostability and catalytic function. Therefore, a fully occupied binuclear manganese metal cluster is required for optimal catalysis and thermostability.
Altering the binuclear manganese cluster of arginase diminishes thermostability and catalytic function.,Scolnick LR, Kanyo ZF, Cavalli RC, Ash DE, Christianson DW Biochemistry. 1997 Aug 26;36(34):10558-65. PMID:9265637[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
