The interactions of a range of monocarboxylic acids with tetramethoxysilane Si(OMe)(4) (TMOS), in methanol (MeOH), have been investigated by using (1)H, (13)C and (29)Si solution-phase NMR spectroscopy and electrospray mass spectrometry (ESMS). Si(OMe)(4) acts as a catalyst/reagent in the selective methylation of 2-hydroxycarboxylic acids (2HOAs) in MeOH at room temperature: glycolic acid, lact...

Pinonic acid, a C10-monocarboxylic acid with a hydrophilic -CO2H group and a hydrophobic hydrocarbon backbone, is a key intermediate oxidation product of α-pinene - an important monoterpene compound in biogenic emission processes that influences the atmosphere. Molecular interaction between cis-pinonic acid and water is essential for understanding its role in the formation and growth of pinene-...

The free radicals formed by H-atom abstraction from many hydroxy-, monoand polycarboxylic acids have been characterized by a variety of fastkinetic techniques [1—4]. These studies led to some general conclusions, formulated by Hayon et al. [2], concerning the spectra and pK’s of the radicals. i) The absorption spectra of a-carboxyalkyl radicals have maxima in the spectral range of 320 to 350 nm...

BETWEEN SOLUBLE MONOCARBOXYLIC ACIDS AND ALIPATIC SIDE CHAINS OF IOM IN CARBONACEOUS CHONDRITES. Y. Huang, Y. Wang, M.R. Alexandre, A.J. Brearley, and C. M. O’D. Alexander, Department of Geological Sciences, Brown University, RI02912 ([email protected]), Department of Earth and Planetary Sciences, University of New Mexico, NM87131, Department of Terrestrial Magnetism, Carnegie Institutio...

Stomatal guard cells play a key role in gas exchange for photosynthesis and in minimizing transpirational water loss from plants by opening and closing the stomatal pore. The bulk of the osmotic content driving stomatal movements depends on ionic fluxes across both the plasma membrane and tonoplast, the metabolism of organic acids, primarily Mal (malate), and its accumulation and loss. Anion ch...

Previous experiments revealed that DHH1, a RNA helicase involved in the regulation of mRNA stability and translation, complemented the phenotype of a Saccharomyces cerevisiae mutant affected in the expression of genes coding for monocarboxylic-acids transporters, JEN1 and ADY2 (Paiva S, Althoff S, Casal M, Leao C. FEMS Microbiol Lett, 1999, 170:301-306). In wild type cells, JEN1 expression had ...

In the sand-fly mid gut, Leishmania promastigotes are exposed to acute changes in nutrients, e.g. amino acids (AAs). These metabolites are the main energy sources for the parasite, crucial for its differentiation and motility. We analysed the migratory behaviour and morphological changes produced by aliphatic, monocarboxylic, dicarboxylic, heterocyclic and sulphur-containing AAs in Leishmania a...