On page 255 of this issue, Luecke et al. (1) reveal the structure of bacteriorhodopsin, an active transport protein, frozen in midstroke. Bacteriorhodopsin is a membrane protein that uses a photon of visible light as an energy source to transport a proton across the membrane against an electrochemical gradient, resulting in proton release on one side of the membrane and proton uptake on the opp...

background: among diverse protein purification systems, affinity chromatography is the most attractive one in the purification process of coagulation factors. coagulation factor vii is a plasma serine protease that has a significant role in natural human hemostasis and its recombinant form such as aryoseventm, has been applied in clinical treatment of bleeding disorders. immunoaffinity chromato...

Onychomycosis is a fungal nail infection which is relatively common and difficult to treat. Treatment modalities include nail avulsion, surgical debridement and combination therapy with oral and topical antifungal drugs. In spite of a host of available drugs, clinical cure rates remain discouraging. Drug toxicities, prolonged regimens, lack of patient compliance, and high keratin affinity of dr...

A series of insecticidal dihydroagarofuran sesquiterpene polyesters were isolated from the root bark of Chinese bittersweet (Celastrus angulatus Max). A previous study indicated that these compounds affect the digestive system of insects, and aminopeptidase N3 and V-ATPase have been identified as the most putative target proteins by affinity chromatography. In this study, the correlation betwee...

The ionization mechanism in dopant-assisted atmospheric pressure photoionization and the effect of solvent on the ionization efficiency was studied using 7 naphthalenes and 13 different solvent systems. The ionization efficiency was 1-2 orders of magnitude higher with dopant than without, indicating that the photoionization of the dopant initiates the ionization process. In positive ion mode, t...

Extended hydrogen bond networks are a common structural motif of enzymes. A recent analysis proposed quantum delocalization of protons as a feature present in the hydrogen bond network spanning a triad of tyrosines (Y(16), Y(32), and Y(57)) in the active site of ketosteroid isomerase (KSI), contributing to its unusual acidity and large isotope shift. In this study, we utilized amber suppression...

Uptake of glutamate from the synaptic cleft is mediated by high affinity transporters and is driven by Na(+), K(+), and H(+) concentration gradients across the membrane. Here, we characterize the molecular mechanism of the intracellular pH change associated with glutamate transport by combining current recordings from excitatory amino acid carrier 1 (EAAC1)-expressing HEK293 cells with a rapid ...

Epithelial brush-border membrane vesicles (BBMVs) of lobster (Homarus americanus) hepatopancreas were formed by a Mg2+ precipitation technique. In these BBMVs, [14C]glycylsarcosine ([14C]Gly-Sar) uptake was stimulated by a transmembrane proton gradient. transmembrane K+ diffusion potential (inside negative) stimulated [14C]Gly-Sar uptake above that observed with short-circuited vesicles, while ...