G-protein coupled receptors (GPCRs) comprise the largest protein family and mediate the vast majority of signal transduction processes in the body. Until recently GPCRs were not considered to be voltage dependent. Newly it was shown for several GPCRs that the first step in GPCR activation, the binding of agonist to the receptor, is voltage sensitive: Voltage shifts the receptor between two stat...

Cultured human urinary bladder carcinoma cells ( JTC -32) were used to investigate the regulation of insulin receptors by dexamethasone. When the cells were preincubated with dexamethasone at 37 degrees C, insulin binding sites increased up to 24 h. A large increase in insulin binding sites took place for 14 h of preincubation with dexamethasone. At lower concentrations of dexamethasone (less t...

Sera of camelids contain both conventional heterotetrameric antibodies and unique functional heavy (H)-chain antibodies (HCAbs). The H chain of these homodimeric antibodies consists of one antigen-binding domain, the VHH, and two constant domains. HCAbs fail to incorporate light (L) chains owing to the deletion of the first constant domain and a reshaped surface at the VHH side, which normally ...

Tentoxin, a cyclic tetrapeptide, induces chlorosis in certain plant species. It inactivated photophosphorylation and coupling factor 1 (CF(1)) ATPase in lettuce, a sensitive species. This effect was due to binding of tentoxin with CF(1) at a single site (affinity constant 1.3 to 20 x 10(7) M(-1)). Neither AMP nor adenyl-5'-yl imidodiphosphate appeared to bind to this site. In radish, an insensi...

This article examines the influence of three common stabilizing agents (citrate, poly(vinylpyrrolidone) (PVP), and branched poly(ethylenimine) (BPEI)) on the attachment affinity of silver nanoparticles to ceramic water filters. Citrate-stabilized silver nanoparticles were found to have the highest attachment affinity (under conditions in which the surface potential was of opposite sign to the f...

The influence of heparin on the reaction between thrombin and plasminogen activator inhibitor-l (PAI-1) has been examined. With a 50-fold excess of PAI-1, the rate constant for the inhibition of thrombin was 458 mol/L"s", which increased to 5,000 mol/L"s" in the presence of 25 pg/mL unfractionated heparin or heparin with low affinity for antithrombin. The effect of low affinity heparin was then...

Resealed chromaffin-granule ;ghosts' were used to study the steady-state kinetics of catecholamine transport. The pump has a high affinity for (-)-noradrenaline, (-)-adrenaline, tyramine and 5-hydroxytryptamine (serotonin), but a lower affinity for (+)-noradrenaline. The measured rates of incorporation do not conform to Michaelis-Menten kinetics, but affinity constants for the former substrates...

Single-chain antibody mutants have been evolved in vitro with antigen-binding equilibrium dissociation constant K(d) = 48 fM and slower dissociation kinetics (half-time > 5 days) than those for the streptavidin-biotin complex. These mutants possess the highest monovalent ligand-binding affinity yet reported for an engineered protein by over two orders of magnitude. Optimal kinetic screening of ...

1. Several ring-substituted derivatives of diphenyleneiodonium catalyse the exchange of Clh and OHions across the inner membrane of rat liver mitochondria. They also inhibit state 3 and state 3u oxidations of glutamate plus malate in the presence of Cl more than in its absence. Most have activities similar to diphenyleneiodonium, although 2,4dichlorodiphenyleneiodonium is up to 50 times more ac...

The complex of yeast cytochrome c peroxidase and cytochrome c is a paradigm of the biological electron transfer (ET). Building on seven decades of research, two different models have been proposed to explain its functional redox activity. One postulates that the intermolecular ET occurs only in the dominant, high-affinity protein-protein orientation, while the other posits formation of an addit...