Inactivation of cytochrome P-450 during catalytic oxidation of a 3-[(arylthio)ethyl]sydnone:  N-vinyl heme formation via insertion into the iron-nitrogen bond

Montellano, Paul R. Ortiz de; Grab, Lawrence A.

doi:10.1021/ja00278a037

Cited by 44 publications

(15 citation statements)

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“…3–6,10,11,12 In particular, Ortiz de Montellano and co-workers observed porphyrin modification in the reaction of P450 and model Fe-porphyrin complexes with 3-[[2-(2,4,6-trimethylphenyl)thio]ethyl]-4-methylsydnone 5 or diazoacetophenone 11 and proposed an intramolecular carbene insertion reaction to account for their observations. To investigate whether an analogous pathway is operative in our system, we analyzed the porphyrins from the reaction of EDA and 1 using purified BM3-HStar and quenched after 15 s and 1 min.…”

Section: Resultsmentioning

confidence: 99%

“…Transfer of the carbene fragment to a second substrate forms product and regenerates the active ferrous enzyme. Even though the formation of iron carbenoids in P450s has been described in the literature, − our report in 2013 was the first example of their use in productive enzymatic catalysis. Indeed, P450s were reported to undergo suicide inactivation in the presence of halothane and CCl 4 , whereby a putative iron carbenoid led to covalent modification of the enzymes and irreversible loss of activity.…”

Section: Introductionmentioning

confidence: 84%

“…Similarly, the decomposition of 3-[[2-(2,4,6-trimethylphenyl)thio]ethyl]-4-methylsydnone by rat liver P450 was proposed to proceed via an iron carbenoid intermediate that reacted with the heme cofactor to form N -vinylprotoporphyrin IX. 5 …”

Section: Introductionmentioning

confidence: 99%

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Identification of Mechanism-Based Inactivation in P450-Catalyzed Cyclopropanation Facilitates Engineering of Improved Enzymes

et al. 2016

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Following the recent discovery that heme proteins can catalyze the cyclopropanation of styrenyl olefins with high efficiency and selectivity, interest in developing new enzymes for a variety of non-natural carbene transfer reactions has burgeoned. The fact that diazo compounds and other carbene precursors are known mechanism-based inhibitors of P450s, however, led us to investigate if they also interfere with this new enzyme function. We present evidence for two inactivation pathways that are operative during cytochrome P450-catalyzed cyclopropanation. Using a combination of UV-Vis, mass spectrometry, and proteomic analyses, we show that the heme cofactor and several nucleophilic side chains undergo covalent modification by ethyl diazoacetate (EDA). Substitution of two of the affected residues with less-nucleophilic amino acids led to a more than two-fold improvement in cyclopropanation performance (total TTN). Elucidating the inactivation pathways of heme protein-based carbene transfer catalysts should aid in the optimization of this new biocatalytic function.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 84%

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Identification of Mechanism-Based Inactivation in P450-Catalyzed Cyclopropanation Facilitates Engineering of Improved Enzymes

et al. 2016

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“…Further collapse of 58 and 59 afforded the obtained mixtures of compounds (Scheme 13.19). Oxidation with ozone of 4-methylsydnones leads to pyruvate esters (Scheme 13.20) [66].…”

Section: Ring Cleavagementioning

confidence: 99%

Oxadiazoles

Romeo¹,

Chiacchio²

2011

Modern Heterocyclic Chemistry

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“…It has been postulated that iron-carbene complexes could be formed upon reaction of diazo compounds with cytochrome P-450 [53]. Model studies of reactions between Fe(I1) porphyrins and the diazo compounds RCOCN2CH3 (R = Ph or CH3) led very recently to the isolation and complete characterization of porphyrin-Fe(I1)-C(CH,)COR carbene complexes [54] (Eqn 16).…”

Section: -2-4 Complexesformed By Interaction Of Diazo Compounds Wmentioning

confidence: 99%

Chemical model systems for drug‐metabolizing cytochrome‐P‐450‐dependent monooxygenases

Mansuy

Battioni

1989

European Journal of Biochemistry

179

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Monooxygenases are widely distributed enzymes which catalyze dioxygen activation using two electrons and two protons, with the insertion of one oxygen atom from O2 into a substrate and the formation of water (Eqn 1).A great number of these monooxygenases contain a heme protein called cytochrome P-450 which is the site of dioxygen activation. These cytochrome-P-450-dependent monooxygenases are involved in many steps of the biosynthesis and biodegradation of endogenous compounds such as steroids, fatty acids, prostaglandins and leukotrienes. They also play a key role in the oxidative metabolism of exogenous compounds such as drugs and other environmental products allowing their elimination from living organisms. Because of their wide distribution in living organisms and their very important role in biochemistry, pharmacology and toxicology, cytochromes P-450 have been the subject of many studies during the last 20 years. Thus, much is known about the structure and function of cytochromes P-450 (for recent reviews, see [l -41) and more than 60 cytochromes P-450 from various origins have been sequenced [5].However, because of the high molecular mass of cytochromes P-450 (about 50 kDa), it is still difficult to determine the detailed mechanism of substrate oxidations and the nature of the iron intermediates involved in these processes. In particular, it is difficult to determine the molecular structure of the iron-metabolite complexes formed from time to time during the metabolism of some classes of substrates. A possible way to solve these problems is to use biomimetic chemical systems involving iron-porphyrins.In fact, iron-porphyrin model systems for cytochromes P-450 may be used for three main purposes. The first is to determine the nature of the iron complexes involved as intermediates in the catalytic cycle of dioxygen activation and substrate hydroxylation by cytochrome P-450. Model ironporphyrin complexes for all these intermediates except one have been prepared and completely characterized by various spectroscopic techniques. Their structures have been established by X-ray analysis. The spectroscopic characteristics of these model complexes have been found to be very similar to Ahhreviutions. TMP, tetramesitylporphyrin; TPP, meso-tetraphenylporphyriu; TDCPP, tetra-2,6-dichlorophenylporphyrin.those of the corresponding enzymatic complexes and the use of these models has largely contributed to our present detailed knowledge of the catalytic cycle of cytochrome P-450. This first interest of the use of models has been described in previous reviews (see for instance [6 -91) and will not be treated in this article.A second objective of the use of chemical models for cytochromes P-450 is to understand as much as possible about the mechanisms of cytochrome P-450 during these reactions. In particular, the preparation and complete characterization of models for the cytochrome-P-450 -iron -metabolite complexes formed during the metabolism of some drugs or exogenous compounds should allow us to determine the chemical fu...

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Inactivation of cytochrome P-450 during catalytic oxidation of a 3-[(arylthio)ethyl]sydnone: N-vinyl heme formation via insertion into the iron-nitrogen bond

Cited by 44 publications

References 1 publication

Identification of Mechanism-Based Inactivation in P450-Catalyzed Cyclopropanation Facilitates Engineering of Improved Enzymes

Identification of Mechanism-Based Inactivation in P450-Catalyzed Cyclopropanation Facilitates Engineering of Improved Enzymes

Oxadiazoles

Chemical model systems for drug‐metabolizing cytochrome‐P‐450‐dependent monooxygenases

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