Methane monooxygenase catalyzed oxygenation of 1,1-dimethylcyclopropane. Evidence for radical and carbocationic intermediates.

  title={Methane monooxygenase catalyzed oxygenation of 1,1-dimethylcyclopropane. Evidence for radical and carbocationic intermediates.},
  author={F. Ruzicka and D. S. Huang and M. Donnelly and P. Frey},
  volume={29 7},
Methane monooxygenase catalyzes the oxygenation of 1,1-dimethylcyclopropane in the presence of O2 and NADH to (1-methylcyclopropyl)methanol (81%), 3-methyl-3-buten-1-ol (6%), and 1-methyl-cyclobutanol (13%). Oxygenation by 18O2 using the purified enzyme proceeds with incorporation of 18O into the products. Inasmuch as methane monooxygenase catalyzes the insertion of O from O2 into a carbon-hydrogen bond of alkanes, (1-methylcyclopropyl)methanol appears to be a conventional oxygenation product… Expand
Mechanistic insights into C-H activation from radical clock chemistry: oxidation of substituted methylcyclopropanes catalyzed by soluble methane monooxygenase from Methylosinus trichosporium OB3b.
The results show that the occurrence of rearranged products fails to correlate with either the chemical nature of the C-H bond being broken, which is very similar for all of the methylcyclopropanes studied here, or the magnitude of the radical k(r) value, which suggests that the steric properties of the substrate play an important role in determining the outcome of the reaction. Expand
Stabilization of carbinylcarbocation by and nucleophilic attack upon cyclopropyl and trans-2, trans-3-diphenylcyclopropyl rings. Reduction of (trans-2, trans-3-diphenylcyclopropyl)methanol and (trans-2, trans-3-diphenylcyclopropyl)cyclopropylmethanol
Abstract ( trans -2, trans -3-Diphenylcyclopropyl)methanol (R 1 OH) can be reduced to ( trans -2, trans -3-diphenylcyclopropyl)methane with NaBH 3 CN in the presence of (PhO) 3 PMeI and ( trans -2,Expand
Substrate radical intermediates in soluble methane monooxygenase.
It is proposed that a molecule of NOB acts simultaneously as a substrate and a spin-trap for MMO, yielding the long-lived radical and supporting a stepwise mechanism for MMO. Expand
Oxygen-18 tracer studies of enzyme reactions with radical/cation diagnostic probes.
  • L. Moe, B. Fox
  • Chemistry, Medicine
  • Biochemical and biophysical research communications
  • 2005
Norcarane proved to be an excellent substrate for the diiron enzyme toluene 4-monooxygenase and its engineered isoforms, with kcat and coupling between NADH utilization and total hydroxylated products comparable to that determined for toluenes, the natural substrate. Expand
Kinetic characterization of the inactivation of ammonia monooxygenase in Nitrosomonas europaea by alkyne, aniline and cyclopropane derivatives.
The kinetic mechanisms of seven inactivators of ammonia oxidation activity in cells of the nitrifying bacterium, Nitrosomonas europaea were investigated and all seven compounds appear to be mechanism-based inactivator of AMO. Expand
Oxidation reactions performed by soluble methane monooxygenase hydroxylase intermediates H(peroxo) and Q proceed by distinct mechanisms.
It is shown for the first time that an inverse trend exists between the rate constant of reaction with H(peroxo) and the C-H bond strength of the hydrocarbon examined for those substrates in which C- H bond activation is rate-determining. Expand
Xylene monooxygenase, a membrane-spanning non-heme diiron enzyme that hydroxylates hydrocarbons via a substrate radical intermediate
Mechanistic investigations using whole-cell assays will facilitate more rapid screening of structure–function relationships and the identification of novel oxygenases and the construction of a picture of the key metalloenzymes and the mechanisms they use in selected parts of the global carbon cycle without requiring the isolation of every protein involved. Expand
Oxidation of Ultrafast Radical Clock Substrate Probes by the Soluble Methane Monooxygenase from Methylococcus capsulatus(Bath)*
Radical clock substrate probes were used to assess the viability of a discrete substrate radical species in the mechanism of hydrocarbon oxidation by the soluble methane monooxygenase (sMMO), and results strongly suggest that there is no such substrate radical intermediate. Expand
Transient intermediates of the methane monooxygenase catalytic cycle.
Three new intermediates of the catalytic cycle of the soluble form of methane monooxygenase (MMO) isolated from Methylosinus trichosporium OB3b have been detected using transient kinetic techniques, suggesting that product release is the rate-limiting step in catalysis. Expand
Dioxygen Activation and Methane Hydroxylation by Soluble Methane Monooxygenase: A Tale of Two Irons and Three Proteins.
Different aspects of catalysis by the MMO proteins are examined, including the mechanisms of dioxygen activation at the diiron site and substrate hydroxylation by the activated oxygen species. Expand


Spectroscopic properties of the hydroxylase of methane monooxygenase.
The hydroxylase component of methane monooxygenase (EC 1.25), which catalyzes the oxidation of methane to methanol, has been studied by visible, electron spin resonance and X-ray spectroscopies and generates ESR-detectable states that appear to emanate from mixed-valence binuclear sites. Expand
Oxidation of Hydrocarbons by Methane Monooxygenases from a Variety of Microbes
Publisher Summary Methane monooxygenase is the enzyme responsible for the initial oxygenation of methane to methanol. The methanotrophs (methane-oxidizing bacteria) are divided into two typesExpand
Methane monooxygenase from Methylosinus trichosporium OB3b. Purification and properties of a three-component system with high specific activity from a type II methanotroph.
The data presented here provide the first evidence based on catalysis that the site of the monooxygenation reaction is located on the hydroxylase, and implies a new mechanism for the generation of highly reactive oxygen capable of insertion into unactivated carbon-hydrogen bonds. Expand
ESR studies of protein A of the soluble methane monooxygenase from Methylococcus capsulatus (Bath)
Abstract ESR spectroscopy of protein A, proposed to be the oxygenase component of the methane monooxygenase (methane, NAD(P)H:oxygen oxidoreductase (hydroxylating), EC from MethylococcusExpand
Cytochrome P-450
ing species placed symmetrically between the endo and exo hydrogens could result in a G value of I, with subsequent asymmetric placement of the oxygen atom selectively at the exo face. TheExpand
Purification and characterization of component A of the methane monooxygenase from Methylococcus capsulatus (Bath).
Methylococcus capsulatus (Bath) possesses a multi-component methane monooxygenase which catalyzes in vivo the conversion of methane to methanol. Component A of this enzyme system, believed to be theExpand
Aliphatic hydroxylation by highly purified liver microsomal cytochrome P-450. Evidence for a carbon radical intermediate.
A very large isotope effect and a significant amount of epimerization for the hydroxylation of norbornane by cytochrome P-450, suggest an initial hydrogen abstraction to give a carbon radical intermediate. Expand
Protein B of soluble methane monooxygenase from Methylococcus capsulatus (Bath). A novel regulatory protein of enzyme activity.
A purification protocol is described here for the previously uncharacterized protein B of the soluble methane monooxygenase from the obligate methanotroph Methylococcus capsulatus (Bath), possessing the capacity to convert the enzyme from an oxidase to an oxygenase. Expand
Oxygenation of methane by methane-grown Pseudomonas methanica and Methanomonas methanooxidans.
The results showed that the oxygen in methanol was derived exclusively from gaseous oxygen in both micro-organisms, and control experiments confirmed that there was negligible incorporation of the oxygen atom from water into meethanol. Expand
Small-ring compounds—XXIX A reinvestigation of the solvolysis of cyclopropylcarbinyl chloride in aqueous ethanol. Isomerization of cyclopropylcarbinol
The solvolysis of cyclopropylcarbinyl chloride in 80% ethanol is attended by substantial rearrangement—not only do the solvolysis products include cyclobutyl and allylcarbinyl alcohols and ethylExpand