Methyl group

About: Methyl group is a research topic. Over the lifetime, 11550 publications have been published within this topic receiving 154360 citations. The topic is also known as: methyl group & methyl end.

Characterization of an acetate-decarboxylating, non-hydrogen-oxidizing methane bacterium.

Abstract: A methanogenic bacterium, commonly seen in digested sludge and referred to as the "fat rod" or Methanobacterium soehngenii, has been enriched to a monoculture and is characterized. Cells are gramnegative, non-motile and appear as straight rods with flat ends. They form filaments which can grow to great lengths. The structure of the outer cell envelop is similar to Methanospirillum hungatii. The organism grows on a mineral salt medium with acetate as the only organic component. Acetate is the energy source, and methane is formed exclusively from the methyl group. Acetate and carbon dioxide act as sole carbon source and are assimilated in a molar ratio of about 1.9:1. The reducing equivalents necessary to build biomass from these two precursors are obtained from the total oxidation of some acetate. Hydrogen is not used for methane formation and is not needed for growth. Formate is cleaved into hydrogen and carbon dioxide. Coenzyme M was found to be present at levels of 0.35 nmol per mg of dry cells and F420 amounted to 0.55 microgram per mg protein. The mean generation time was 9 days at 33 degrees C.

Transformation of toluene and benzene by mixed methanogenic cultures

Abstract: The aromatic hydrocarbons toluene and benzene were anaerobically transformed by mixed methanogenic cultures derived from ferulic acid-degrading sewage sludge enrichments. In most experiments, toluene or benzene was the only semicontinuously supplied carbon and energy source in the defined mineral medium. No exogenous electron acceptors other than CO2 were present. The cultures were fed 1.5 to 30 mM unlabeled or 14C-labeled aromatic substrates (ring-labeled toluene and benzene or methyl-labeled toluene). Gas production from unlabeled substrates and 14C activity distribution in products from the labeled substrates were monitored over a period of 60 days. At least 50% of the substrates were converted to CO2 and methane (greater than 60%). A high percentage of 14CO2 was recovered from the methyl group-labeled toluene, suggesting nearly complete conversion of the methyl group to CO2 and not to methane. However, a low percentage of 14CO2 was produced from ring-labeled toluene or from benzene, indicating incomplete conversion of the ring carbon to CO2. Anaerobic transformation pathways for unlabeled toluene and benzene were studied with the help of gas chromatography-mass spectrometry. The intermediates detected are consistent with both toluene and benzene degradation via initial oxidation by ring hydroxylation or methyl oxidation (toluene), which would result in the production of phenol, cresols, or aromatic alcohol. Additional reactions, such as demethylation and ring reduction, are also possible. Tentative transformation sequences based upon the intermediates detected are discussed.

Comparison of self-assembled monolayers on gold: coadsorption of thiols and disulfides

Abstract: : Ordered, organic monolayers were formed on gold slides by adsorption from ethanol of HS(CH2)10CH2OH, HS(CH2)10CH3, S(CH2)10CH2OH2, S(CH2)10Ch32, and of binary mixtures of these molecules in which one component was terminated by a hydrophobic methyl group and one by a hydrophilic alcohol group. The compositions of the monolayers were determined by X-ray photoelectron spectroscopy (XPS). Wettability was used as a probe of the chemical composition and structure of the surface of the monolayer. When monolayers were formed in solutions containing mixtures of a thiol and a disulfide, adsorption of the thiol was strongly preferred (approx. 75:1). Monolayer, Gold, Surface, Contact angles, Thiols, Disulfides.