2cep
From Proteopedia
(New page: 200px<br /><applet load="2cep" size="450" color="white" frame="true" align="right" spinBox="true" caption="2cep, resolution 2.2Å" /> '''ROLE OF MET-230 IN IN...) |
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| - | [[Image:2cep.jpg|left|200px]]<br /><applet load="2cep" size=" | + | [[Image:2cep.jpg|left|200px]]<br /><applet load="2cep" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2cep, resolution 2.2Å" /> | caption="2cep, resolution 2.2Å" /> | ||
'''ROLE OF MET-230 IN INTRAMOLECULAR ELECTRON TRANSFER BETWEEN THE OXYFERRYL HEME AND TRP 191 IN CYTOCHROME C PEROXIDASE COMPOUND II'''<br /> | '''ROLE OF MET-230 IN INTRAMOLECULAR ELECTRON TRANSFER BETWEEN THE OXYFERRYL HEME AND TRP 191 IN CYTOCHROME C PEROXIDASE COMPOUND II'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The kinetics of electron transfer from cytochrome c (CC) to yeast | + | The kinetics of electron transfer from cytochrome c (CC) to yeast cytochrome c peroxidase (CcP) compound I were studied by flash photolysis and stopped-flow spectroscopy. Flash photolysis studies employed horse CC derivatives labeled at specific lysine amino groups with (dicarboxybipyridine)bis-(bipyridine)ruthenium (Ru-CC). Initial electron transfer from Ru-CC reduced the indole radical on Trp-191 of CcP compound I [CMPI(IV,R.)], producing CMPII(IV,R). This reaction was biphasic for each of several Ru-CC derivatives, with rate constants which varied according to the position of the Ru label. For Ru-27-CC labeled at lysine 27, rate constants of 43,000 and 1600 s-1 were observed at pH 5.0 in 2 mM acetate. After reduction of the indole radical by Ru-CC, intramolecular electron transfer from Trp-191 to the oxyferryl heme in CMPII(IV,R) was observed, producing CMPII(III,R.). The rate constant and extent of this intramolecular electron transfer reaction were independent of both the protein concentration and the Ru-CC derivative employed. The rate constant decreased from 1100 s-1 at pH 5 to 550 s-1 at pH 6, while the extent of conversion of CMPII(IV,R) to CMPII(III,R.) decreased from 56% at pH 5 to 29% at pH 6. The reaction was not detected at pH 7.0 and above. The pH dependence of the rate and extent of this internal electron transfer reaction paralleled the pH dependence of the rate of bimolecular reduction of CMPII(IV,R) by native horse CC measured by stopped-flow spectroscopy at high ionic strength.(ABSTRACT TRUNCATED AT 250 WORDS) |
==About this Structure== | ==About this Structure== | ||
| - | 2CEP 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 as [http://en.wikipedia.org/wiki/ligand ligand]. 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:// | + | 2CEP 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> as [http://en.wikipedia.org/wiki/ligand ligand]. 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=2CEP OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Saccharomyces cerevisiae]] | [[Category: Saccharomyces cerevisiae]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Han, G | + | [[Category: Han, G W.]] |
[[Category: Kraut, J.]] | [[Category: Kraut, J.]] | ||
| - | [[Category: Miller, M | + | [[Category: Miller, M A.]] |
[[Category: HEM]] | [[Category: HEM]] | ||
[[Category: oxidoreductase(h2o2(a))]] | [[Category: oxidoreductase(h2o2(a))]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:47:54 2008'' |
Revision as of 14:47, 21 February 2008
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ROLE OF MET-230 IN INTRAMOLECULAR ELECTRON TRANSFER BETWEEN THE OXYFERRYL HEME AND TRP 191 IN CYTOCHROME C PEROXIDASE COMPOUND II
Overview
The kinetics of electron transfer from cytochrome c (CC) to yeast cytochrome c peroxidase (CcP) compound I were studied by flash photolysis and stopped-flow spectroscopy. Flash photolysis studies employed horse CC derivatives labeled at specific lysine amino groups with (dicarboxybipyridine)bis-(bipyridine)ruthenium (Ru-CC). Initial electron transfer from Ru-CC reduced the indole radical on Trp-191 of CcP compound I [CMPI(IV,R.)], producing CMPII(IV,R). This reaction was biphasic for each of several Ru-CC derivatives, with rate constants which varied according to the position of the Ru label. For Ru-27-CC labeled at lysine 27, rate constants of 43,000 and 1600 s-1 were observed at pH 5.0 in 2 mM acetate. After reduction of the indole radical by Ru-CC, intramolecular electron transfer from Trp-191 to the oxyferryl heme in CMPII(IV,R) was observed, producing CMPII(III,R.). The rate constant and extent of this intramolecular electron transfer reaction were independent of both the protein concentration and the Ru-CC derivative employed. The rate constant decreased from 1100 s-1 at pH 5 to 550 s-1 at pH 6, while the extent of conversion of CMPII(IV,R) to CMPII(III,R.) decreased from 56% at pH 5 to 29% at pH 6. The reaction was not detected at pH 7.0 and above. The pH dependence of the rate and extent of this internal electron transfer reaction paralleled the pH dependence of the rate of bimolecular reduction of CMPII(IV,R) by native horse CC measured by stopped-flow spectroscopy at high ionic strength.(ABSTRACT TRUNCATED AT 250 WORDS)
About this Structure
2CEP is a Single protein structure of sequence from Saccharomyces cerevisiae with as ligand. Active as Cytochrome-c peroxidase, with EC number 1.11.1.5 Full crystallographic information is available from OCA.
Reference
Role of methionine 230 in intramolecular electron transfer between the oxyferryl heme and tryptophan 191 in cytochrome c peroxidase compound II., Liu RQ, Miller MA, Han GW, Hahm S, Geren L, Hibdon S, Kraut J, Durham B, Millett F, Biochemistry. 1994 Jul 26;33(29):8678-85. PMID:8038157
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