Acid Sensing Ion Channels (ASICs) detect extracellular proton signals and are involved in synaptic transmission and pain sensation. ASIC subunits assemble into homo- and heteromeric channels composed of three subunits. Single molecule imaging revealed that heteromers composed of ASIC1a and ASIC2a, which are widely expressed in the central nervous system, have a flexible 2:1/1:2 stoichiometry. I...

Previous work (Birnberg, Jayroe, Hanson 1982 Plant Physiol 70: 511-516) demonstrated that corn mitochondria (Zea mays L.) can accumulate citrate by a malate- and phosphate-independent proton symporter. This uptake and symport of other ions were investigated. Passive swelling experiments indicated that corn mitochondria can accumulate several other anions by proton symport, but only isocitrate i...

Hydrogen bonds are ubiquitous in enzyme active sites, providing binding interactions and stabilizing charge rearrangements on substrate groups over the course of a reaction. But understanding the origin and magnitude of their catalytic contributions relative to hydrogen bonds made in aqueous solution remains difficult, in part because of complexities encountered in energetic interpretation of t...

Proton pumping of the vacuolar-type H(+)-ATPase into the lumen of the central plant organelle generates a proton gradient of often 1-2 pH units or more. Although structural aspects of the V-type ATPase have been studied in great detail, the question of whether and how the proton pump action is controlled by the proton concentration on both sides of the membrane is not understood. Applying the p...

The multistage mass spectrometric (MS/MS and MS3) gas-phase fragmentation reactions of methionine side-chain sulfonium ion containing peptides formed by reaction with a series of para-substituted phenacyl bromide (XBr where X=CH2COC6H4R, and R=--COOH, --COOCH3, --H, --CH3 and --CH2CH3) alkylating reagents have been examined in a linear quadrupole ion trap mass spectrometer. MS/MS of the singly ...

DFT(B3LYP) studies on first protonation step of a series of Cu(II) complexes of some tripodal tetraamines with general formula N[(CH(2))(n)NH(2)][(CH(2))(m)NH(2)][(CH(2))(p)NH(2)] (n = m = p = 2, tren; n = 3, m = p = 2, pee; n = m = 3, p = 2, ppe; n = m = 3, tpt; n = 2, m = 3, p = 4, epb; and n = m = 3, p = 4; ppb) are reported. First, the gas-phase proton macroaffinity of all latter complexes ...

ATP synthase uses a unique rotary mechanism to couple ATP synthesis and hydrolysis to transmembrane proton translocation. The F(1) subcomplex has three catalytic nucleotide binding sites, one on each beta subunit, with widely differing affinities for MgATP or MgADP. During rotational catalysis, the sites switch their affinities. The affinity of each site is determined by the position of the cen...

An analytical approach for the interpretation of multicomponent heterogeneous adsorption or complexation isotherms in terms of multidimensional affinity spectra is presented. Fourier transform, applied to analyze the corresponding integral equation, leads to an inversion formula which allows the computation of the multicomponent affinity spectrum underlying a given competitive isotherm. Althoug...

the efficacy of activation methods and coupling were studied in the context of performance in batch and fixed bed binding experiments utilizing cell culture fluids or blood plasma as feedstock. conclusions were drawn regarding selection of solid phase according to pore size, rigidity, ph stability, chemistry of derivation and activation, and gross concentration of immobilized ligand required fo...