Spectrophotometric determination of reaction stoichiometry and equilibrium constants of metallochromic indicators. II. The Ca2+-arsenazo III complexes.

@article{Dorogi1981SpectrophotometricDO,
  title={Spectrophotometric determination of reaction stoichiometry and equilibrium constants of metallochromic indicators. II. The Ca2+-arsenazo III complexes.},
  author={P. Dorogi and E. Neumann},
  journal={Biophysical chemistry},
  year={1981},
  volume={13 2},
  pages={
          125-31
        }
}
The analytical method described in the preceding article was applied to spectrophotometric Ca2+-titrations of the metallochromic indicator arsenazo III (Ar). At various reactant concentrations it was determined that Ar forms 1:1,1:2 and 2 : 1 complexes with calcium. The equilibrium constants and extinction coefficients at 602 nm were determined. Corrected to zero ionic strength at 293 K and pH 7.0, the reactions Ca + Ar = CaAr, CaAr + Ar = CaAr2 and CaAr + Ca = Ca2Ar are associated with… Expand
Spectrophotometric determination of reaction stoichiometry and equilibrium constants of metallochromic indicators. III. Antipyrylazo III complexing with Ca2+ and acetylcholine receptor protein.
TLDR
This is the first reported indication that antipyrylazo III binds to biological material and questions the usefulness of this dye as a Ca indicator in biological systems. Expand
Arsenazo I and tetramethylmurexide as optical calcium indicators.
Calcium-binding stoichiometry, dissociation equilibrium constants at zero ionic strength @Lo), and molar extinction difference coefficients (At,) at the wavelength )r of the metallochromic indicatorsExpand
Spectrophotometric determination of reaction stoichiometry and equilibrium constants of metallochromic indicators. I. General calculational method.
A calculational method is developed for spectrophotometric determination of stoichiometrics and individual equilibrium constants in the complexing of metal ions with metallochromic indicators.Expand
Kinetics and mechanism of Ca2+ binding to arsenazo III and antipyrylazo III.
  • P. Dorogi
  • Chemistry, Medicine
  • Biochimica et biophysica acta
  • 1984
TLDR
Dependence of the relaxation rate of arsenazo III on dye and Ca2+ concentrations indicates the presence of both CaAr and CaAr2 complexes, with the Ca Ar2 form being responsible for the slow, 10-20 ms relaxation of this dye. Expand
Stoichiometries of arsenazo III-Ca complexes.
TLDR
It is suggested that equilibrium calibration of the dye with calcium cannot be used directly to satisfactorily relate transient absorbance changes in physiological preparations to calcium concentration changes since several stoichiometrically distinct complexes with different absorbances could be formed at different rates. Expand
Kinetic calibration of the calcium indicator arsenazo III. I: Stopped-flow spectroscopy
Abstract Stopped-flow studies of the calcium-arsenazo III (Ar) system exhibit reaction time constants ranging from 4 to 20 ms, mainly caused by the formation of CaAr and CaAr2 complexes ( [ Ca ] 0 =Expand
Evaluation of Calcium - Arsenazo III Stoichiometry in the Presence and Absence of Egta at Various pH
Abstract The calcium titration experiments were performed with 9 uM and 100 uM concentrations of Arsenazo III (Az) at various pH°s in the presence as well as in the absence of ethyleneExpand
Kinetic scheme for Ca2+-arsenazo III interactions.
TLDR
The relatively slow rate-limiting step sets a limit for the use of arsenazo III to study the kinetics of Ca2+ processes in cell biology. Expand
Arsenazo III, a resonance raman indicator with high selectivity for Ca2+
The accurate and rapid measurement of PM levels of free Ca2’ in cells is very important in view of the regulatory role of Ca’+, and the existence of rapid changes in its concentration duringExpand
The use of metallochromic Ca indicators in skeletal muscle.
TLDR
Absorbance signals recorded with metallochromic indicators in skeletal muscle fibers show rapid time courses that probably closely track the fast kinetic process of Ca++ release and retrapping by the sarcoplasmic reticulum, but the formation of more than one complex in cuvette calibrations suggest that care needs to be taken in the deconvolution of in vivo absorbance signals. Expand
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A calculational method is developed for spectrophotometric determination of stoichiometrics and individual equilibrium constants in the complexing of metal ions with metallochromic indicators.Expand
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