J.D. Erfle

Valinomycin inhibited methane synthesis in Methanobacteriumthermoautotrophicum

Abstract Methanobacterium thermoautotrophicum cells, incubated anaerobically under H2 in 0.1 M KCl or 0.1 M NaCl, above pH 7.5, are interior acid with respect to the incubation medium. The pH gradient thus established can be discharged by either carbonyl cyanide m-chlorophenylhydrazone or valinomycin at high concentration (17μM). In these cells, which actively synthesize CH4 from CO2 and H2, methanogenesis is strongly inhibited when the pH gradient is discharged.

The accumulation of citrate cycle intermediates in rat liver cells oxidizing palmitate

Abstract 1. 1. Rat liver cells oxidizing [1- 14 C]palmitate or [1- 14 C]palmitoyl-carnitine show linear rates of 14 CO 2 output after an initial 10-min lag period. 2. 2. During this interval, there was considerable accumulation of 14 C in water soluble organic acids, acetyl-CoA, and acetyl-carnitine, but much less radioactivity accumulated in palmitoyl-CoA, phospholipid or neutral lipid fractions. 3. 3. It was concluded that the lag period in 14 CO 2 output was not the result of rate limiting reactions involving palmitate uptake, transport or activation to the CoA or carnitine ester, but resulted from an initial accumulation of 14 C in acetyl-CoA, acetyl-carnitine, and water-soluble organic acids which subsequently were oxidized to 14 CO 2 .

Methane production by cell-free particulate fraction of rumen bacteria.

Rumen bacteria retained methanogenic activity when stored at −60° under H2. This activity, which resides in Methanobacterium ruminantium and Methanobacterium mobilis, is not lost when the cells are broken, as has been suggested. Unlike in Methanosarcina barkerii and Methanobacterium M.o.H., in rumen bacteria methanogenic enzymes are not soluble but readily precipitated at 15,000 g. Methane was synthesized from tetrahydrofolate derivatives but at slower rates than from CO2. From the data, it was not possible to determine if methyl- and methylene tetrahydrofolate were oxidized to CO2 prior to reduction to CH4. In room light, CH3-B12 was reduced to CH4 non-enzymatically in the presence of protein. When the reactions were carried out in the dark, very little CH4 was formed from CH3-B12 by rumen bacterial enzymes. The cell-free particulate fraction did not require added ATP for methanogenesis but showed an absolute requirement for H2.

An evaluation of the chemical identity oe acylcarnitine esters oe hexadecanoic acids

Abstract The infrared and NMR data on the acylcarnitine esters of β-substituted hexadecanoic acids, the synthesis and metabolism of which were described previously, are discussed in view of the recent controversy regarding the identity of these compounds. The chemical purity and identity of the compounds in question have been assessed on the basis of chemical degradation, chromatographie and spectrographic techniques. It is concluded that these compounds were chemically and stereochemically authentic.