Optimal conditions for RecA protein-mediated DNA strand exchange include 6-8 mm Mg(2+) in excess of that required to form complexes with ATP. We provide evidence that the free magnesium ion is required to mediate a conformational change in the RecA protein C terminus that activates RecA-mediated DNA strand exchange. In particular, a "closed" (low Mg(2+)) conformation of a RecA nucleoprotein fil...

Water exchange around a free magnesium ion and paired with carbonate in aqueous solution was studied using energy methods. Both rigid-ion polarizable force field based on the AMOEBA model were examined. The parameters adjusted to accurately reproduce hydration structures of solution. pairing energies calculated both fields found be excellent agreement experimental data. Metadynamics simulations...

Competitive divalent (magnesium and calcium) or monovalent (potassium, lithium and sodium) ion exchange and its influence on a membrane potential formation was studied at biological ligands (BL) such as adenosine triphosphate (ATP), asparagine (Asn) and glutamine (Gln) sites. The sites are dispersed electrochemically in membranes made of the conducting polymers (CPs)--poly(N-methylpyrrole) (PMP...

Co-localization of the elements calcium, potassium, sodium and magnesium with sequestering organelles has been achieved by application of two microscopy techniques on the same cell. Organelles were first localized by laser scanning confocal microscopy (LSCFM) using fluorescent organelle stains. The same cells were then analyzed for elemental distribution with ion microscopy. This approach has i...

In the rescue treatment of acute asthma, injected and inhalant magnesium are relatively weak having demonstrated value only in severe illness, although theoretical and laboratory considerations suggest that magnesium should be strongly effective as an asthma rescue agent. It was hypothesized that a mouth-lung biologically closed electric circuit (BCEC) exists capable of nearly instantly transpo...

In previous papers some of the characteristics and the extent of the inhibition of alkaline phosphatase activity by a-amino acids were evaluated (1). The first concern of the present study was to investigate the influence of magnesium ion on this inhibition. Since the results which were obtained in this connection indicated the possibility that a-amino acids might exert their inhibitory action ...

OBJECTIVE To test the hypothesis that glucose ingestion leads to a decrease in plasma ionized calcium (iCa) and ionized magnesium (iMg) during the third trimester of pregnancy. METHODS We studied 54 women who underwent a 50 g glucose challenge test (GCT) and 27 women who underwent a 3-hour 100 g glucose tolerance test (GTT) because of an abnormal GCT. Plasma glucose was measured with an autom...

Magnesium sulphate has previously been shown therapeutic in porcine malignant hyperthermia. It was given intravenously in doses of 99 mg. kg -~ before and 277 mgkg -~ after an episode of malignant hyperthermia had been produced by halothane 1.5 per cent, in agroup of four malignant hyperthermia susceptible swine. Two groups of four additional MH susceptible and MH resistant swine received a con...

Acetate kinase catalyzes the magnesium-dependent transfer of the gamma-phosphate of ATP to acetate. The recently determined crystal structure of the Methanosarcina thermophila enzyme identifies it as a member of the sugar kinase/Hsc70/actin superfamily based on the fold and the presence of five putative nucleotide and metal binding motifs that characterize the superfamily. Residues from four of...

1. Increased bronchial smooth muscle contractility with consequent bronchial hyperreactivity are characteristic physiopathological events of asthma. Since magnesium intervenes in calcium transport mechanisms and intracellular phosphorylation reactions, it constitutes an important determinant of the contraction/relaxation state of bronchial smooth muscle. In the present study we investigated the...