Na/K-ATPase pumps expel three Na ions and import two K ions for each ATP hydrolyzed, generating the ion gradients across the membrane that are essential to the life of all animal cells. Each transport cycle comprises a sequence of conformational transitions that permit extracellular K ions to access the binding sites in phosphorylated pumps (E2P conformations; Fig. 1) and cytoplasmic Na ions to...

Potassium ion (K) is the most abundant intracellular metal ion in the body and plays an important role in biological activities. Fabrication of K recognition and response smart materials is of both scientific and technological interests for various applications. Recently, our group have developed a series kinds of K-recognizable responsive smart materials based on 15-crown-5 as K recognizing re...

Hodgkin and Huxley (1952) demonstrated the presence of voltage-activated sodium (Na ) and potassium (K ) permeabilities in the squid giant axon. Ever since then, biophysicists have tried to understand how voltage activates the ionic pathways responsible for the action potential. Hodgkin and Huxley (1952) concluded that there had to be charges or charge dipoles in the membrane that move in respo...

K(+) channels distinguish K(+) from Na(+) in the selectivity filter, which consists of four ion-binding sites (S1-S4, extracellular to intracellular) that are built mainly using the carbonyl oxygens from the protein backbone. In addition to ionic discrimination, the selectivity filter regulates the flow of ions across the membrane in a gating process referred to as C-type inactivation. A charac...

A time-of-flight mass spectrometer with orthogonal acceleration and soft X-rays from synchrotron radiation were utilized to measure near-edge X-ray absorption fine structure (NEXAFS) spectra of carbon and oxygen in phenol and the corresponding ionic fragments following core excitation. The photon energies were in the range of 284-298 eV for the carbon K-edge and 529.5-554.5 eV for the oxygen K-...

In single-column anion-exchange chromatography, the retention volume of some monovalent inorganic anions (Cl(-), Br(-), NO(3)(-), NCS(-) and NO(2)(-)) were observed as a function of the pH of a mobile phase at a fixed concentration of 2-phenylmalonic acid or 1,4-benzenediacetic acid used as an eluent. The experimental retention volume of such an anion was decreased with an increase in the pH of...

Vitamin K deficiency or administration of vitamin K antagonists results in the biosynthesis of abnormal des-gamma-carboxy forms of the vitamin K-dependent proteins. Monoclonal antibody H-11 binds several vitamin K-dependent proteins at a determinant that includes the first two residues of gamma-carboxyglutamic acid. Antibody H-11 binds fully carboxylated prothrombin and protein C in the presenc...

We measured unidirectional K 1 inand efflux through an inward rectifier K channel (IRK1) expressed in Xenopus oocytes. The ratio of these unidirectional fluxes differed significantly from expectations based on independent ion movement. In an extracellular solution with a K 1 concentration of 25 mM, the data were described by a Ussing flux-ratio exponent, n 9 , of z 2.2 and was constant over a v...

Potassium channels are trans-membrane proteins, which selectively transport K+ ions across cell membranes and play a key role in regulating the physiology of excitability cells and signal transduction pathways. Bothutous Schach (BS) scorpion venom consists of several polypeptides that could modulate ion channels. In this study, the effects of BS crude venom on passive and active electrophysiolo...