637-95-6Relevant academic research and scientific papers
Potentiation of mitochondrial Ca2+ sequestration by taurine
Palmi, Mitri,Youmbi, Gisele Tchuisseu,Fusi, Fabio,Sgaragli, Gian P.,Dixon, Henry B.F.,Frosini, Maria,Tipton, Keith F.
, p. 1123 - 1131 (1999)
The effects of taurine (2-aminoethanesulphonic acid) and its analogues, 2-aminoethylarsonic acid, 2-hydroxyethanesulphonic (isethionic) acid, 3-aminopropanesulphonic acid, 2-aminoethylphosphonic acid, and N,N-dimethyltaurine, were studied on the transport of Ca2+ by mitochondria isolated from rat liver. Taurine enhanced Ca2+ uptake in an apparently saturable process, with a K(m) value of about 2.63 mM. Taurine behaved as an uncompetitive activator of Ca2+ uptake, increasing both the apparent K(m) and V(max) values of the process. This effect was not modified in the presence of cyclosporin A (CsA). N,N-Dimethyltaurine also stimulated Ca2+ uptake at higher concentrations, but there was no evidence that the process was saturable over the concentration range used (1-10 mM). Aminoethylarsonate was a weak inhibitor of basal Ca2+ uptake, but inhibited that stimulated by taurine in an apparently competitive fashion (K(i) = 0.05 mM). The other analogues had no significant effects on this process. Taurine either in the presence or the absence of CsA had no effect on Ca2+ release induced by 200 nM ruthenium red. Thus, the mechanism of taurine-enhanced Ca2+ accumulation appears to involve stimulation of Ca2+ uptake via the uniport system rather than inhibition of Ca2+ release via the ion (Na+/Ca2+ and/or H+/Ca2+) exchangers or by taurine modulating the permeability transition of the mitochondrial inner membrane. Overall, these findings indicate an interaction of taurine with an as yet unidentified mitochondrial site which might regulate the activity of the uniporter. The unique role of taurine in modulating mitochondrial Ca2+ homeostasis might be of particular importance under pathological conditions that are characterised by cell Ca2+ overload, such as ischaemia and oxidative stress. Copyright (C) 1999 Elsevier Science Inc.
Covalently Bonded Polymeric Zwitterionic Stationary Phase for Simultaneous Separation of Inorganic Cations and Anions
Jiang, Wen,Irgum, Knut
, p. 333 - 344 (1999)
A novel polymer-based zwitterionic separation material was synthesized by a two-step reaction, in which 2-hydroxyethyl methacrylate-ethylene dimethacrylate copolymer beads were first activated with epichlorohydrin, whereafter (2-dimethylamino)ethanesulfonic acid inner salt was coupled to the epoxide groups on the activated beads in a quaternizing reaction. The resulting material carried strong/strong charge zwitterionic pendant groups, whose charge properties did not change over a wide pH range. It was capable of separating inorganic anions and cations both independently and simultaneously using aqueous solutions of perchloric acid or perchlorate salts as eluent It was found that the retention of cations and anions depended on the individual ions in the analyte, not on type of salt injected, as reported for ODS columns dynamically coated with zwitterionic detergents using water only as eluent. This study also revealed that both the concentration and the water structure related properties of the eluent ions were important for the retention of ionic species. The mechanism appears to involve the interaction of the chaotropic anion component with the quaternary ammonium group, resulting in an increasing cation-exchange capacity of the zwitterion up to a perchloric add eluent concentration of c.a. 10 mM. Above this concentration the material appears to become saturated, and the retention times of both cations and anions become practically independent of the HClO4 concentration.
