ENDOR Study of Oxoiron(IV) Porphyrin π-Cation Radical Complexes as Models for Compound I of Heme Enzymes

2009 ◽  
Vol 38 (1) ◽  
pp. 68-69 ◽  
Author(s):  
Akihiro Takahashi ◽  
Yasunori Ohba ◽  
Seigo Yamauchi ◽  
Hiroshi Fujii
Keyword(s):  
Cation Radical ◽  
Heme Enzymes ◽  
Compound I

Direct Resonance Raman Evidence for a Trans Influence on the Ferryl Fragment in Models of Compound I Intermediates of Heme Enzymes

1996 ◽  
Vol 118 (12) ◽  
pp. 2929-2935 ◽  
Author(s):  
Kazimierz Czarnecki ◽  
Shay Nimri ◽  
Zeev Gross ◽  
Leonard M. Proniewicz ◽  
James R. Kincaid
Keyword(s):  
Resonance Raman ◽  
Heme Enzymes ◽  
Compound I ◽  
Trans Influence ◽  
Direct Resonance

Molecular engineering of cytochrome P450 and myoglobin for selective oxygenations

2004 ◽  
Vol 08 (03) ◽  
pp. 279-289 ◽  
Author(s):  
Takafumi Ueno ◽  
Takahiro Ohki ◽  
Yoshihito Watanabe
Keyword(s):  
Cytochrome P450 ◽  
Protein Engineering ◽  
Rational Design ◽  
Oxygen Carrier ◽  
Molecular Engineering ◽  
Heme Enzymes ◽  
Compound I ◽  
Dynamic Nature ◽  
Enzyme Substrate ◽  
First Time

Aspects of protein engineering of cytochrome P450 (P450) and myoglobin ( Mb ) to construct selective oxygenation catalysts have been described. Heme enzymes are known as biocatalysts for various oxidations but the design of substrate specificity has still remained one of the significant challenges because of dynamic nature of enzyme-substrate interactions. In particular, P450s are the most interesting targets among the heme enzymes because they are able to catalyze many types of monooxygenations such as hydroxylation, epoxidation, and sulfoxidation with high selectivity. Thus, many researchers have made efforts to convert the selectivity for natural substrates into that for unnatural substrates by several protein engineering approaches. On the other hand, we have reported a rational design of Mb to convert its oxygen carrier function into that of peroxidase or peroxygenase. The Mb mutants prepared in our work afford oxo-ferryl porphyrin radical cation (compound I) as observable species in Mb for the first time. Furthermore, some of the mutants we have constructed are useful for enantioselective oxygenations by oxygen transfer from the Mb -compound I to substrates.

scholarly journals Scavenging of oxygen radicals by heme peroxidases.

1996 ◽  
Vol 43 (4) ◽  
pp. 673-678 ◽  
Author(s):  
L Gebicka ◽  
J L Gebicki
Keyword(s):  
Horseradish Peroxidase ◽  
Hydroxyl Radicals ◽  
Superoxide Radical ◽  
Cation Radical ◽  
Compound I ◽  
Superoxide Radical Anion ◽  
Form Compound ◽  
Activity Loss ◽  
Heme Peroxidases ◽  
Compound Ii

The reactions of two heme peroxidases, horseradish peroxidase and lactoperoxidase and their compounds II (oxoferryl heme intermediates, Fe(IV) = O or ferric protein radical Fe(III)R.) and compounds III (resonance hybrids [Fe(III)-O2-. Fe(II)-O2] with superoxide radical anion generated enzymatically or radiolytically, and with hydroxyl radicals generated radiolytically, were investigated. It is suggested that only the protein radical form of compound II of lactoperoxidase reacts with superoxide, whereas compound II of horseradish peroxidase, which exists only in oxoferryl form, is unreactive towards superoxide. Compound III of the investigated peroxidases does not react with superoxide. The lactoperoxidase activity loss induced by hydroxyl radicals is closely related to the loss of the ability to form compound I (oxoferryl porphyrin pi-cation radical, Fe(IV) = O(Por+.) or oxoferryl protein radical Fe(IV) = O(R.)). On the other hand, the modification of horseradish peroxidase induced by hydroxyl radicals has been reported to cause also restrictions in substrate binding (Gebicka, L. & Gebicki, J.L., 1996, Biochimie 78, 62-65). Nevertheless, it has been found that only a small fraction of hydroxyl radicals generated homogeneously does inactivate the enzymes.

scholarly journals A comprehensive test set of epoxidation rate constants for iron(iv)–oxo porphyrin cation radical complexes

2015 ◽  
Vol 6 (2) ◽  
pp. 1516-1529 ◽  
Author(s):  
Mala A. Sainna ◽  
Suresh Kumar ◽  
Devesh Kumar ◽  
Simonetta Fornarini ◽  
Maria Elisa Crestoni ◽  
...  
Keyword(s):  
Oxygen Atom ◽  
Gas Phase ◽  
Cation Radical ◽  
Compound I ◽  
Oxygen Atom Transfer ◽  
Test Set ◽  
Extensive Test ◽  
Comprehensive Test ◽  
First Time ◽  
Porphyrin Cation

Trends in oxygen atom transfer to Compound I of the P450 models with an extensive test set have been studied and show a preferred regioselectivity of epoxidation over hydroxylation in the gas-phase for the first time.

Identification of a Porphyrin .pi. Cation Radical in Ascorbate Peroxidase Compound I

Biochemistry ◽  
1995 ◽  
Vol 34 (13) ◽  
pp. 4342-4345 ◽  
Author(s):  
William R. Patterson ◽  
Thomas L. Poulos ◽  
David B. Goodin
Keyword(s):  
Ascorbate Peroxidase ◽  
Cation Radical ◽  
Compound I
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