In vitro calibration of the equilibrium reactions of the metallochromic indicator dye antipyrylazo III with calcium

The equilibrium reactions of the metallochromic indicator dye Antipyrylazo III with calcium at physiological ionic strength have been investigated spectrophotometrically. Dye absorbance as a function of wavelength was measured at various total dye and calcium concentrations. Analysis of the absorban...

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Bibliographic Details
Published inBiophysical journal Vol. 51; no. 3; pp. 383 - 393
Main Authors Hollingworth, S., Aldrich, R.W., Baylor, S.M.
Format Journal Article
LanguageEnglish
Published Bethesda, MD Elsevier Inc 01.03.1987
Biophysical Society
Subjects
Analytical, structural and metabolic biochemistry
Biological and medical sciences
Calcium
Fundamental and applied biological sciences. Psychology
Indicators and Reagents
Inorganic compounds
Kinetics
Mathematics
Naphthalenesulfonates
Other biological molecules
Spectrophotometry
Molecular association
Metallochromic indicator
Muscle
Calibration
Calcium
In vitro
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Summary:The equilibrium reactions of the metallochromic indicator dye Antipyrylazo III with calcium at physiological ionic strength have been investigated spectrophotometrically. Dye absorbance as a function of wavelength was measured at various total dye and calcium concentrations. Analysis of the absorbance spectra indicated that at pH 6.9 at least three calcium:dye complexes form, with 1:1, 1:2, and possibly 2:2 stoichiometries. The dissociation constant and the changes in dye extinction coefficients on formation of the 1:2 complex, the main complex which forms when Antipyrylazo III is used to study cytoplasmic calcium transients, have been characterized.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
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ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(87)83360-X