1dj5
From Proteopedia
(New page: 200px<br /><applet load="1dj5" size="450" color="white" frame="true" align="right" spinBox="true" caption="1dj5, resolution 1.93Å" /> '''CRYSTAL STRUCTURE OF...) |
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| - | [[Image:1dj5.gif|left|200px]]<br /><applet load="1dj5" size=" | + | [[Image:1dj5.gif|left|200px]]<br /><applet load="1dj5" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1dj5, resolution 1.93Å" /> | caption="1dj5, resolution 1.93Å" /> | ||
'''CRYSTAL STRUCTURE OF R48A MUTANT OF CYTOCHROME C PEROXIDASE WITH N-HYDROXYGUANIDINE BOUND'''<br /> | '''CRYSTAL STRUCTURE OF R48A MUTANT OF CYTOCHROME C PEROXIDASE WITH N-HYDROXYGUANIDINE BOUND'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Heme enzymes are capable of catalyzing a range of oxidative chemistry with | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 1DJ5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae] with HEM and HGU as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cytochrome-c_peroxidase Cytochrome-c peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.5 1.11.1.5] Full crystallographic information is available from [http:// | + | 1DJ5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae] with <scene name='pdbligand=HEM:'>HEM</scene> and <scene name='pdbligand=HGU:'>HGU</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cytochrome-c_peroxidase Cytochrome-c peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.5 1.11.1.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DJ5 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Saccharomyces cerevisiae]] | [[Category: Saccharomyces cerevisiae]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Goodin, D | + | [[Category: Goodin, D B.]] |
[[Category: Hirst, J.]] | [[Category: Hirst, J.]] | ||
[[Category: HEM]] | [[Category: HEM]] | ||
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[[Category: oxidoreductase]] | [[Category: oxidoreductase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:17:03 2008'' |
Revision as of 10:17, 21 February 2008
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CRYSTAL STRUCTURE OF R48A MUTANT OF CYTOCHROME C PEROXIDASE WITH N-HYDROXYGUANIDINE BOUND
Overview
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.
About this Structure
1DJ5 is a Single protein structure of sequence from Saccharomyces cerevisiae with and as ligands. Active as Cytochrome-c peroxidase, with EC number 1.11.1.5 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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