5RLA: Altering The Binuclear Manganese Cluster Of Arginase Diminishes Thermostability And Catalytic Function

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.
PDB ID: 5RLADownload
MMDB ID: 7760
PDB Deposition Date: 1997/5/7
Updated in MMDB: 2012/12
Experimental Method:
x-ray diffraction
Resolution: 2.74  Å
Source Organism:
Similar Structures:
Biological Unit for 5RLA: trimeric; determined by author and by software (PISA)
Molecular Components in 5RLA
Label Count Molecule
Proteins (3 molecules)
Arginase(Gene symbol: Arg1)
Molecule annotation
Chemicals (3 molecules)
* Click molecule labels to explore molecular sequence information.

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