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1dj1

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{{STRUCTURE_1dj1| PDB=1dj1 | SCENE= }}
{{STRUCTURE_1dj1| PDB=1dj1 | SCENE= }}
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'''CRYSTAL STRUCTURE OF R48A MUTANT OF CYTOCHROME C PEROXIDASE'''
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===CRYSTAL STRUCTURE OF R48A MUTANT OF CYTOCHROME C PEROXIDASE===
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==Overview==
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Heme enzymes are capable of catalyzing a range of oxidative chemistry with high specificity, depending on the surrounding protein environment. We describe here a reaction catalyzed by a mutant of cytochrome c peroxidase, which is similar but distinct from those catalyzed by nitric-oxide synthase. In the R48A mutant, an expanded water-filled cavity was created above the distal heme face. N-hydroxyguanidine (NHG) but not guanidine was shown to bind in the cavity with K(d) = 8.5 mM, and coordinate to the heme to give a low spin state. Reaction of R48A with peroxide produced a Fe(IV)=O/Trp(.+) center capable of oxidizing either NHG or N(omega)-hydroxyarginine (NHA), but not arginine or guanidine, by a multi-turnover catalytic process. Oxidation of either NHG or NHA by R48A did not result in the accumulation of NO, NO(2)(-), NO(3)(-), urea, or citrulline, but instead afforded a yellow product with absorption maxima of 257 and 400 nm. Mass spectrometry of the derivatized NHA products identified the yellow species as N-nitrosoarginine. We suggest that a nitrosylating agent, possibly derived from HNO, is produced by the oxidation of one molecule of substrate. This then reacts with a second substrate molecule to form the observed N-nitroso products. This complex chemistry illustrates how the active sites of enzymes such as nitric-oxide synthase may serve to prevent alternative reactions from occurring, in addition to enabling those desired.
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{{ABSTRACT_PUBMED_10722697}}
==About this Structure==
==About this Structure==
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[[Category: Cavity mutant]]
[[Category: Cavity mutant]]
[[Category: Heme enzyme]]
[[Category: Heme enzyme]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 23:08:29 2008''

Revision as of 20:08, 30 June 2008

Template:STRUCTURE 1dj1

CRYSTAL STRUCTURE OF R48A MUTANT OF CYTOCHROME C PEROXIDASE

Template:ABSTRACT PUBMED 10722697

About this Structure

1DJ1 is a Single protein structure of sequence from Saccharomyces cerevisiae. Full crystallographic information is available from OCA.

Reference

Unusual oxidative chemistry of N(omega)-hydroxyarginine and N-hydroxyguanidine catalyzed at an engineered cavity in a heme peroxidase., Hirst J, Goodin DB, J Biol Chem. 2000 Mar 24;275(12):8582-91. PMID:10722697

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