Multidrug antiporters of the major facilitator superfamily couple proton translocation to the extrusion of cytotoxic molecules. The conformational changes that underlie the transport cycle and the structural basis of coupling of these transporters have not been elucidated. Here we used extensive double electron-electron resonance measurements to uncover the conformational equilibrium of LmrP, a...

The addition of nucleophiles to electron-deficient alkenes represents one of the more general and commonly used strategies for the convergent assembly of more complex structures from simple precursors. In this review the addition of diverse protic and organometallic nucleophiles to electron-deficient alkenes followed by enantioselective protonation is summarized. Reactions are first categorized...

Light changes the structure of chloroplasts. This effect was investigated by high resolution electron microscopy, photometric methods, and chemical modification. (a) A reversible contraction of chloroplast membrane occurs upon illumination, dark titration with H(+), or increasing osmolarity. These gross structural changes arise from a flattening of the thylakoids, with a corresponding decrease ...

The hydroxido-bridged dinuclear ruthenium complex 4, which is supported by Tp ligands, has been prepared from protonation of the oxido-bridged dinuclear ruthenium complex 3. Additional protonation of 4, affording the aqua-bridged dinuclear ruthenium complex 5 in situ, and subsequent treatment with NO gave rise to the dicationic dinitrosyl complex 2. These indicate completion of the NO reduction...

A simple interface is proposed for combined quantum mechanical (QM) molecular mechanical (MM) calculations for the systems where the QM and MM regions are connected through covalent bonds. Within this model, the atom that connects the two regions, called YinYang atom here, serves as an ordinary MM atom to other MM atoms and as a hydrogen-like atom to other QM atoms. Only one new empirical param...

The protonation constants of glycine, L-alanine, glycyl-glycine, glycyl-glycyl-glycine and glycyl-L-alanine have been determined in 10-80% (v/v) ethanol-water mixtures at 25 °C and constant ionic strength (0.1 mol L-1 sodium perchlorate), by potentiometric technique and calculated using a suitable computer program, which employs a nonlinear least-squares method. The effect of solvent compositio...

-Phenamiphos interacted with homoionic montmoriUonites of Ca 2+, Mn 2+, Co 2+, and Ni 2+ to form interlayer complexes having basal spacings of about 16.5/~. In the infrared spectra, the v-PO bands were displaced towards lower frequencies suggesting that this group interacted with the exchange cations. Moreover, a small shoulder at 1600 cm -~ indicated the partial protonation of the phenamiphos....

The coil-to-globule transition of poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) in aqueous solution was investigated by all-atomistic molecular dynamics simulations. The polymer consistent force field (PCFF) was applied to the PDMAEMA model with a proper protonation state. The structural analysis indicates a distinct difference in the hydration state of particular functional groups of PDMAE...

Protonation states are sometimes crucial for free energy calculations to predict binding ability of molecules to receptors, a main subject for drug design. This mini-review seeks to identify the importance of knowing the influence of pH in such studies to better achieve correct predictions for drug candidates. Protonation states, for both proteins and drugs, need to be considered in docking stu...

Protonation of polyaniline base with lightly sulfonated polystyrene in polar solvents such its dimethyl sulfoxide and N-methyl-2-py~olidone was investigated by UV-Vis absorption spectra. As the molar ratio of sulfonated polystyrenelpolyaniline increases, the conversion from polyaniline base form to salt form is observed owing 10 incrensed protonation. The isosbestic point clearly shows that qui...