2cj0: Difference between revisions

Chloroperoxidase (CPO) is a heme-thiolate enzyme that catalyzes hydrogen, peroxide-dependent halogenation reactions. Structural data on substrate, binding have not been available so far. CPO was therefore crystallized in, the presence of iodide or bromide. One halide binding site was identified, at the surface near a narrow channel that connects the surface with the, heme. Two other halide binding sites were identified within and at the, other end of this channel. Together, these sites suggest a pathway for, access of halide anions to the active site. The structure of CPO complexed, with its natural substrate cyclopentanedione was determined at a, resolution of 1.8 A. This is the first example of a CPO structure with a, bound organic substrate. In addition, structures of CPO bound with, nitrate, acetate, and formate and of a ternary complex with, dimethylsulfoxide (Me2SO) and cyanide were determined. These structures, have implications for the mechanism of compound I formation. Before, binding to the heme, the incoming hydrogen peroxide first interacts with, Glu-183. The deprotonated Glu-183 abstracts a proton from hydrogen, peroxide. The hydroperoxo-anion then binds at the heme, yielding compound, 0. Glu-183 protonates the distal oxygen of compound 0, water is released, and compound I is formed.

2CJ0 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Leptoxyphium_fumago Leptoxyphium fumago] with NAG, MAN, MN, NO3, HEM and EDO as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Chloride_peroxidase Chloride peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.10 1.11.1.10] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2CJ0 OCA].  

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