Automatic determination of ligand purity and apparent dissociation constant (Kapp) in Ca2+/Mg2+ buffer solutions and the Kapp for Ca2+/Mg2+ anion binding in physiological solutions from Ca2+/Mg2+-macroelectrode measurements

Kay, J.W. , Steven, R.J., McGuigan, J.A.S. and Elder, H. (2008) Automatic determination of ligand purity and apparent dissociation constant (Kapp) in Ca2+/Mg2+ buffer solutions and the Kapp for Ca2+/Mg2+ anion binding in physiological solutions from Ca2+/Mg2+-macroelectrode measurements. Computers in Biology and Medicine, 38(1), pp. 101-110. (doi: 10.1016/j.compbiomed.2007.07.008) (PMID:17854794)

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Abstract

Calibration of Ca<sup>2+</sup>/Mg<sup>2+</sup> macroelectrodes and flurochromes in the nmolar and Îśmolar range, respectively, require the use of buffer solutions. In these buffers the apparent dissociation constant (<i>K</i><sub>app</sub>) has to be measured since calculation based on tabulated constants gives variable results. The ligand concentration [Ligand]<sub>T</sub> has also to be estimated. The most accurate and general method for measuring both is the ligand optimisation method based on macroelectrode potential measurements, but this iterative method is time consuming, thus limiting its application. This paper describes an automatic program based on the method, which on entering the measured macroelectrode data calculates <i>K</i><sub>app</sub>, [Ligand]<sub>T</sub> and the ionised concentration [X<sup>2+</sup>] within minutes. This optimisation method cannot be used at Kapp values greater than 0.1 mM, but can be extended into this region if the anion concentration is known. The program has been modified to cover this eventuality. Ca<sup>2+</sup>/Mg<sup>2+</sup> macroelectrodes in conjunction with these programs offer an accurate, routine method for determining <i>K</i><sub>app</sub> and [Ligand]<sub>T</sub> in buffer solutions at the appropriate ionic strength, temperature and pH and the <i>K</i><sub>app</sub> for divalent cations binding to physiological anions under experimental conditions.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:McGuigan, Prof John and Elder, Dr Hugh and Kay, Dr James
Authors: Kay, J.W., Steven, R.J., McGuigan, J.A.S., and Elder, H.
Subjects:Q Science > QH Natural history > QH301 Biology
R Medicine > R Medicine (General)
Q Science > QA Mathematics > QA75 Electronic computers. Computer science
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > School of Life Sciences
College of Science and Engineering > School of Mathematics and Statistics > Statistics
Journal Name:Computers in Biology and Medicine
Publisher:Elsevier
ISSN:0010-4825
ISSN (Online):1879-0534
Published Online:12 September 2007

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