Advancing understanding of actinide(iii) (Ac, Am, Cm) aqueous complexation chemistry

Actinide complexation from aqueous acetic acid/acetate buffered solutions is described. The number of water ligands was directly correlated with the acetate concentration and characterized by X-ray absorption and optical spectroscopy.

Production of the Short Chain Fatty Acid, Acetic Acid/Acetate from Ethanol Metabolism Activates NMDAR

ABSTRACTShort chain fatty acid (SCFA) regulation of neuronal function remains an interesting but poorly understood area of research. The SCFA, acetic acid, the main component of vinegar and the major metabolite of ethanol has been directly linked to altering neuronal function. However, the underlying mechanisms as it relates to alcohol consumption and SCFA regulation of neuronal function have yet to be elucidated. Here we show that local metabolism of ethanol to acetic acid/acetate in the central nucleus of amygdala (CeA) activates glutamatergic N-methyl-D-aspartate receptors (NMDAR) in vivo causing a sympathoexcitatory response. External acetate and intracellular loading of acetic acid in CeA neurons increased neuronal excitability through activation of NMDAR. Furthermore, cultured neurons exposed to acetate showed increased cytosolic calcium which response was abolished by NMDAR antagonist and decreased pH. These findings suggest that acetic acid/acetate is an underestimated bioactive metabolite of ethanol that mediates some effects via an NMDAR-dependent mechanism in the brain. The link between the SCFA, acetic acid/acetate on increased neuronal excitability at least partially through NMDAR may provide a novel avenue for understanding alcohol, metabolic, cardiovascular and neurodegenerative disorders related to alterations in SCFA concentrations in the brain.

Acetobacter aceti Possesses a Proton Motive Force-Dependent Efflux System for Acetic Acid

ABSTRACT Acetic acid bacteria are obligate aerobes able to oxidize ethanol, sugar alcohols, and sugars into their corresponding acids. Among them, Acetobacter and Gluconacetobacter species have very high ethanol oxidation capacity, leading to accumulation of vast amounts of acetic acid outside the cell. Since these bacteria are able to grow in media with high concentrations of acetic acid, they must possess a specific mechanism such as an efflux pump by which they can resist the toxic effects of acetic acid. In this study, the efflux pump of Acetobacter aceti IFO 3283 was examined using intact cells and membrane vesicles. The accumulation of acetic acid/acetate in intact cells was increased by the addition of a proton uncoupler and/or cyanide, suggesting the presence of an energy-dependent efflux system. To confirm this, right-side-out and inside-out membrane vesicles were prepared from A. aceti IFO 3283, and the accumulation of acetic acid/acetate in the vesicles was examined. Upon the addition of a respiratory substrate, the accumulation of acetic acid/acetate in the right-side-out vesicles was largely decreased, while its accumulation was very much increased in the inside-out vesicles. These respiration-dependent phenomena observed in both types of membrane vesicles were all sensitive to a proton uncoupler. Acetic acid/acetate uptake in the inside-out membrane vesicles was dependent not on ATP but on the proton motive force. Furthermore, uptake was shown to be rather specific for acetic acid and to be pH dependent, because higher uptake was observed at lower pH. Thus, A. aceti IFO 3283 possesses a proton motive force-dependent efflux pump for acetic acid.