A highly-selective chloride microelectrode based on a mercuracarborand anion carrier

The chloride gradient plays an important role in regulating cell volume, membrane potential, pH, secretion, and the reversal potential of inhibitory glycine and GABAA receptors. Measurement of intracellular chloride activity, $${{\boldsymbol{a}}}_{{\boldsymbol{Cl}}}^{{\boldsymbol{i}}}$$aCli, using liquid membrane ion-selective microelectrodes (ISM), however, has been limited by the physiochemical properties of Cl− ionophores which have caused poor stability, drift, sluggish response times, and interference from other biologically relevant anions. Most importantly, intracellular $${\bf{HC}}{{\bf{O}}}_{{\bf{3}}}^{-}$$HCO3− may be up to 4 times more abundant than Cl− (e.g. skeletal muscle) which places severe constraints on the required selectivity of a Cl− – sensing ISM. Previously, a sensitive and highly-selective Cl− sensor was developed in a polymeric membrane electrode using a trinuclear Hg(II) complex containing carborane-based ligands, [9]-mercuracarborand-3, or MC3 for short. Here, we have adapted the use of the MC3 anion carrier in a liquid membrane ion-selective microelectrode and show the MC3-ISM has a linear Nernstian response over a wide range of aCl (0.1 mM to 100 mM), is highly selective for Cl− over other biological anions or inhibitors of Cl− transport, and has a 10% to 90% settling time of 3 sec. Importantly, over the physiological range of aCl (1 mM to 100 mM) the potentiometric response of the MC3-ISM is insensitive to $${\bf{HC}}{{\bf{O}}}_{{\bf{3}}}^{-}$$HCO3− or changes in pH. Finally, we demonstrate the biological application of an MC3-ISM by measuring intracellular aCl, and the response to an external Cl-free challenge, for an isolated skeletal muscle fiber.

Аn improved method for preparation of heptyl (4-trifluoroacetyl) benzoate

A convenient three-step method for synthesis of heptyl (4-trifluoroacetyl)benzoate, an important neutral anion carrier, has been developed. The key step of the method is acylation of toluene by trifluoroacetic anhydride in presence of aluminium chloride at –8 – –10 oC. The procedure gives high overall yield and, unlike the earlier methods, does not include any organometallic reagents, therefore allowing scaling it up to several hundred grams, that makes the target compound much more readily available.

A highly-selective chloride microelectrode based on a mercuracarborand anion carrier

ABSTRACTThe chloride gradient plays an important role in regulating cell volume, membrane potential, pH, secretion, and the reversal potential of inhibitory GABAA receptors. Measurement of intracellular chloride activity, , using liquid membrane ion-selective microelectrodes (ISM), however, has been limited by the physiochemical properties of Cl ionophores which have caused poor stability, drift, sluggish response times, and interference from other biologically relevant anions. Most importantly, intracellular HCO3− may be up to 4 times more abundant than Cl− (e.g. skeletal muscle) which places severe constraints on the required selectivity of a Cl – sensing ISM.Previously, a sensitive and highly-selective Cl sensor was developed in a polymeric membrane electrode (Badr et al. 1999) using a trinuclear Hg(II) complex containing carborane-based ligands, [9]-mercuracarborand-3, or MC3 for short. Here, we have adapted the use of the MC3 anion carrier in a liquid membrane ion-selective microelectrode and show the MC3-ISM has a linear Nernstian response over a wide range of aCl (0.1 mM to 100 mM), is highly selective for Cl over other biological anions or inhibitors of Cl transport, and has a response time of less than 5 sec. Importantly, over the physiological range of aCl (1 mM to 100 mM) the potentiometric response of the MC3-ISM is insensitive to HCO3− or changes in pH. Finally, we demonstrate the biological application of an MC3-ISM by measuring intracellular aCl, and the response to an external Cl-free challenge, for an isolated skeletal muscle fiber.

Carrier-mediated solvent bar microextraction coupled with HPLC-DAD for the quantitative analysis of the hydrophilic antihypertensive peptide VLPVPR in human plasma

Aliquat-336, an anion carrier, facilitates the extraction of hydrophilic VLPVPR peptide by Solvent-Bar-Micro-Extraction, achieving sensitive peptide analysis in biological samples.

Full elucidation of the transmembrane anion transport mechanism of squaramides using in silico investigations

The anion carrier mechanism promoted by squaramide-based molecules has been elucidated by molecular dynamics and chloride efflux studies.

Mitochondrial Uncoupling Proteins in Mammals and Plants

Uncoupling proteins (UCPs) belong to a distinct cluster of the mitochondrial anion carrier family. Up to five different uncoupling protein types were found in mitochondria of mammals and plants, and recently in fishes, fungi and protozoa. They exhibit a significantly conserved structure with several motifs specific to either the whole cluster or protein type. Uncoupling proteins, as well as the whole mitochondrial anion carrier gene family, probably emerged in evolution before the separation of animal, fungi, and plant kingdoms and originate from an anion/nucleotide or anion/anion transporter ancestor. Mammalian UCP1, UCP2, UCP3, and plant uncoupling proteins pUCP1 and pUCP2 are similar and seem to form one subgroup, whereas UCP4 and BMCP1 belong to a different group. Molecular, biochemical, and phylogenic data suggest that UCP2 could be considered as an UCP-prototype. UCP1 plays its biological role mainly in the non-shivering thermogenesis while the role of the other types is unknown. However, hypotheses have suggested that they are involved in the general balance of basic energy expenditure, protection from reactive oxygen species, and, in plants, in fruit ripening and seed ontogeny.