Calcium ions probes

Johnson, J.D., Collins, J.H., and Potter, J.D. (1978) Dansylaziridine labeled troponin C. A fluorescent probe of calcium ion binding to the calcium ion-specific regulatory sites./. Biol. Chem. 253, 6451. 

A metal-nucleotide complex that exhibits low rates of ligand exchange as a result of substituting higher oxidation state metal ions with ionic radii nearly equal to the naturally bound metal ion. Such compounds can be prepared with chromium(III), cobalt(III), and rhodi-um(III) in place of magnesium or calcium ion. Because these exchange-inert complexes can be resolved into their various optically active isomers, they have proven to be powerful mechanistic probes, particularly for kinases, NTPases, and nucleotidyl transferases. In the case of Cr(III) coordination complexes with the two phosphates of ATP or ADP, the second phosphate becomes chiral, and the screw sense must be specified to describe the three-dimensional configuration of atoms. 

Mishchenko and Dymarchuk (111) have studied the integral heats of reaction of cellulose with both water and aqueous solutions of electrolytes. A notable maximum in the integral heat of reaction occurs at approximately 2.5m. The authors visualize this sharp maximum as caused by the different behavior above and below the concentration where all the water is intimately tied up as water of hydration. Thus, assuming for calcium chloride that the hydration number is 8 for both the calcium ion and for the chloride ion, a concentration of 2.52m corresponds to complete hydration of the ions. Hence, they suggest that definite hydration numbers exist. It may well be argued, however, that heat of reaction with standard cotton cellulose is a poor probe to choose for studying the aqueous environment. The idea of fixed total hydration of the ions appears a somewhat unlikely interpretation if for no other reason than... 

Coordination chemistry of RE(III) with amino acids has been attracting much interest since the early 1970s after the discovery that certain RE(III) ions could be used as probes of calcium ion binding sites in proteins and enzymes [118, 119], Since then, a large amount of work on the solution and structural chemistry of rare earth-amino acid complexes has been published. The solution studies involve all of the rare earth elements and 13 (Gly, Ala, Val, Leu, Phe, Met, Pro, Ser, Tyr, His, Lys, Trp, and Arg) of the 20 standard amino acids, and more than 100 of the RE(III)-amino acid complexes have been structurally characterized. This section will cover the synthetic, structural, and solution chemistry of these complexes. 

Damall, D.W and Birnbaum, E.R. (1970) Rare earth metal ions as probes of calcium ion binding sites in proteins neodunium(III) acceleration of the activation of trypsinogen. Journal of Biological Chemistry, 245 (23), 6484-6486. 

The antibiotic calcimycin (or A23187) is a widely used probe for calcium ion transport in biological systems. A synthesis of the core of this antibiotic has been developed [15]. Although little stereoselectivity is associated with this method it is rather remarkable in that two ring closures are involved, the first involving hemi-acetal formation and the second an electrophilic closure (Fig. 12). 

A neutral, carrier-based calcium ion-selective microelectrode has been used in the determination of tetraphenylphosphonium ions (used as membrane potential probes) during respiratory-state transitions in rat mitochondria. ... 

Calcium ions are critical in the release of neurotransmitter substances at chemical synapses, and intracellular buffering mechanisms, possibly through a Na/K—ATPase mediated exchange [22], are important in controlling the release of Ca " ions and thus release of the neurotransmitter. The blocking of calcium transport by ruthenium red increases the spontaneous release of neurotransmitter [23]. The utility of these effects as probes is shown by the fact that acetylcholine release induced by tityustoxin, a scorpion neurotoxin, was shown to be enhanced by ruthenium red the stimulation was Ca-dependent and thus the conclusion was reached that free calcium, caused by competitive binding of ruthenium red to receptors, increased the release of acetylcholine [24]. 

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