Activation of Molecular Oxygen in Cytochromes P450

Denisov, Ilia G.; Sligar, Stephen G.

doi:10.1007/978-3-319-12108-6_3

Cited by 32 publications

(62 citation statements)

References 308 publications

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“…While Cpd I is accepted as the primary active species in heme oxygenase chemistry, 9 other intermediates are also capable of catalyzing oxidative reactions. 20,22,23 It should also be mentioned that several of the steps are likely in equilibrium and the rate-limiting step may vary, supporting a more dynamic view of the P450 catalytic cycle. 24 …”

Section: Functionmentioning

confidence: 90%

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Cytochromes P450 for natural product biosynthesis in Streptomyces: sequence, structure, and function

et al. 2017

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Cytochrome P450 enzymes (P450s) are some of the most exquisite and versatile biocatalysts found in nature. In addition to their well-known roles in steroid biosynthesis and drug metabolism in humans, P450s are key players in natural product biosynthetic pathways. Natural products, the most chemically and structurally diverse small molecules known, require an extensive collection of P450s to accept and functionalize their unique scaffolds. In this review, we survey the current catalytic landscape of P450s within the Streptomyces genus, one of the most prolific producers of natural products, and comprehensively summarize the functionally characterized P450s from Streptomyces. A sequence similarity network of >8500 P450s revealed insights into the sequence–function relationships of these oxygen-dependent metalloenzymes. Although only ~2.4% and <0.4% of streptomycete P450s have been functionally and structurally characterized, respectively, the study of streptomycete P450s involved in the biosynthesis of natural products has revealed their diverse roles in nature, expanded their catalytic repertoire, created structural and mechanistic paradigms, and exposed their potential for biomedical and biotechnological applications. Continued study of these remarkable enzymes will undoubtedly expose their true complement of chemical and biological capabilities.

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Section: Functionmentioning

confidence: 90%

“…9,12,17,20–22 However, a description of the sophisticated P450 catalytic cycle is needed to discuss the ability of P450s to catalyze diverse chemical transformations.…”

Section: Functionmentioning

confidence: 99%

Cytochromes P450 for natural product biosynthesis in Streptomyces: sequence, structure, and function

et al. 2017

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“…114 The general mechanism for CYP has been reviewed recently. 116–119 In brief, the binding of substrate displaces a water molecule coordinated to the ferric heme, triggering a change in most, but not all, CYPs from low to high spin with a concomitant change in reduction potential thereby priming the enzyme for reduction. 117,120–123 Following one-electron reduction to the ferrous heme, oxygen binds and undergoes an additional one-electron reduction followed by a series of proton transfers resulting in cleavage of the O–O bond to form compound I and a water molecule.…”

Section: Aerobic Methane Oxidationmentioning

confidence: 99%

“…117,120–123 Following one-electron reduction to the ferrous heme, oxygen binds and undergoes an additional one-electron reduction followed by a series of proton transfers resulting in cleavage of the O–O bond to form compound I and a water molecule. 116,117,124 Compound I is a highly reactive Fe(IV)-oxo species, 125 which abstracts a hydrogen atom from the substrate to form a Fe(IV)-hydroxide intermediate referred to as compound II. 118,126 Compound II rapidly recombines with the substrate radical to yield the ferric heme resting state and the hydroxylated product.…”

Section: Aerobic Methane Oxidationmentioning

confidence: 99%

Methane-Oxidizing Enzymes: An Upstream Problem in Biological Gas-to-Liquids Conversion

2016

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Biological conversion of natural gas to liquids (Bio-GTL) represents an immense economic opportunity. In nature, aerobic methanotrophic bacteria and anaerobic archaea are able to selectively oxidize methane using methane monooxygenase (MMO) and methyl coenzyme M reductase (MCR) enzymes. Although significant progress has been made toward genetically manipulating these organisms for biotechnological applications, the enzymes themselves are slow, complex, and not recombinantly tractable in traditional industrial hosts. With turnover numbers of 0.16–13 s−1, these enzymes pose a considerable upstream problem in the biological production of fuels or chemicals from methane. Methane oxidation enzymes will need to be engineered to be faster to enable high volumetric productivities; however, efforts to do so and to engineer simpler enzymes have been minimally successful. Moreover, known methane-oxidizing enzymes have different expression levels, carbon and energy efficiencies, require auxiliary systems for biosynthesis and function, and vary considerably in terms of complexity and reductant requirements. The pros and cons of using each methane-oxidizing enzyme for Bio-GTL are considered in detail. The future for these enzymes is bright, but a renewed focus on studying them will be critical to the successful development of biological processes that utilize methane as a feedstock.

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“…lyze a wide variety of oxidation reactions, including stereo-and regioselective hydroxylation of non-activated C-H bonds (1). Oxidation of C-H bonds by CYP enzymes with molecular dioxygen, per turnover, requires two electrons that originate from NADH or NADPH (reaction 1) that are transferred sequentially to cytochrome P450, in the case of CYP101 by putidaredoxin (2).…”

mentioning

confidence: 99%

Jumpstarting the cytochrome P450 catalytic cycle with a hydrated electron

Erdoğan

Vandemeulebroucke

Nauser

et al. 2017

Journal of Biological Chemistry

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Cytochrome P450cam (CYP101Fe) regioselectively hydroxylates camphor. Possible hydroxylating intermediates in the catalytic cycle of this well-characterized enzyme have been proposed on the basis of experiments carried out at very low temperatures and shunt reactions, but their presence has not yet been validated at temperatures above 0 °C during a normal catalytic cycle. Here, we demonstrate that it is possible to mimic the natural catalytic cycle of CYP101Fe by using pulse radiolysis to rapidly supply the second electron of the catalytic cycle to camphor-bound CYP101[FeO] Judging by the appearance of an absorbance maximum at 440 nm, we conclude that CYP101[FeOOH] (compound 0) accumulates within 5 μs and decays rapidly to CYP101Fe, with a of 9.6 × 10 s All processes are complete within 40 μs at 4 °C. Importantly, no transient absorbance bands could be assigned to CYP101[FeOpor] (compound 1) or CYP101[FeO] (compound 2). However, indirect evidence for the involvement of compound 1 was obtained from the kinetics of formation and decay of a tyrosyl radical. 5-Hydroxycamphor was formed quantitatively, and the catalytic activity of the enzyme was not impaired by exposure to radiation during the pulse radiolysis experiment. The rapid decay of compound 0 enabled calculation of the limits for the Gibbs activation energies for the conversions of compound 0 → compound 1 → compound 2 → CYP101Fe, yielding a Δ of 45, 39, and 39 kJ/mol, respectively. At 37 °C, the steps from compound 0 to the iron(III) state would take only 4 μs. Our kinetics studies at 4 °C complement the canonical mechanism by adding the dimension of time.

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Activation of Molecular Oxygen in Cytochromes P450

Cited by 32 publications

References 308 publications

Cytochromes P450 for natural product biosynthesis in Streptomyces: sequence, structure, and function

Cytochromes P450 for natural product biosynthesis in Streptomyces: sequence, structure, and function

Methane-Oxidizing Enzymes: An Upstream Problem in Biological Gas-to-Liquids Conversion

Jumpstarting the cytochrome P450 catalytic cycle with a hydrated electron

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