View source for 4cev

[[Image:4cev.gif|left|200px]]<br /><applet load="4cev" size="450" color="white" frame="true" align="right" spinBox="true" 
caption="4cev, resolution 2.7&Aring;" />
'''ARGINASE FROM BACILLUS CALDEVELOX, L-ORNITHINE COMPLEX'''<br />

==Overview==
BACKGROUND: Arginase is a manganese-dependent enzyme that catalyzes the, hydrolysis of L-arginine to L-ornithine and urea. In ureotelic animals, arginase is the final enzyme of the urea cycle, but in many species it has, a wider role controlling the use of arginine for other metabolic purposes, including the production of creatine, polyamines, proline and nitric, oxide. Arginase activity is regulated by various small molecules, including the product L-ornithine. The aim of these structural studies was, to test aspects of the catalytic mechanism and to investigate the, structural basis of arginase inhibition. RESULTS: We report here the, crystal structures of arginase from Bacillus caldovelox at pH 5.6 and pH, 8.5, and of binary complexes of the enzyme with L-arginine, L-ornithine, and L-lysine at pH 8.5. The arginase monomer comprises a single compact, alpha/beta domain that further associates into a hexameric quaternary, structure. The binary complexes reveal a common mode of ligand binding, which places the substrate adjacent to the dimanganese centre. We also, observe a conformational change that impacts on the active site and is, coupled with the occupancy of an external site by guanidine or arginine., CONCLUSIONS: The structures reported here clarify aspects of the active, site and indicate key features of the catalytic mechanism, including, substrate coordination to one of the manganese ions and an orientational, role for a neighboring histidine residue. Stereospecificity for L-amino, acids is found to depend on their precise recognition at the active-site, rim. Identification of a second arginine-binding site, remote from the, active site, and associated conformational changes lead us to propose a, regulatory role for this site in substrate hydrolysis.

==About this Structure==
4CEV is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_caldovelox Bacillus caldovelox] with MN, ORN and GAI as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Arginase Arginase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.3.1 3.5.3.1] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=4CEV OCA]. 

==Reference==
Crystal structures of Bacillus caldovelox arginase in complex with substrate and inhibitors reveal new insights into activation, inhibition and catalysis in the arginase superfamily., Bewley MC, Jeffrey PD, Patchett ML, Kanyo ZF, Baker EN, Structure. 1999 Apr 15;7(4):435-48. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10196128 10196128]
[[Category: Arginase]]
[[Category: Bacillus caldovelox]]
[[Category: Single protein]]
[[Category: Baker, E.N.]]
[[Category: Bewley, M.C.]]
[[Category: Jeffrey, P.D.]]
[[Category: Kanyo, Z.F.]]
[[Category: Patchett, M.L.]]
[[Category: GAI]]
[[Category: MN]]
[[Category: ORN]]
[[Category: arginine hydrolysis]]
[[Category: enzyme]]
[[Category: hydrolase]]
[[Category: manganese metalloenzyme]]
[[Category: nitrogen metabolism]]

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