Enzymatic estimation of protein-ligand association parameters: Determination of organophosphate-albumin binding constants using alkaline phosphatase
✍ Scribed by A. Bannister; R.L. Foster
- Publisher
- Elsevier Science
- Year
- 1977
- Tongue
- English
- Weight
- 533 KB
- Volume
- 82
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
The rates of alkaline phosphatase-catalyzed hydrolyses of p-nitrophenyl phosphate and cY-naphthyl phosphate are depressed by serum albumin. This complexes with the substrates, thus decreasing their concentrations available for catalysis. An expression has been derived describing the influence of albumin on the enzymic reaction. Simplification of this equation yields a form whereby the association parameters for the protein-hgand complex may be determined. The values for organophosphate-albumin dissociation constants are 71 PM for p-nitrophenyl phosphate and 20 pM for cr-naphthyl phosphate. These agree with values estimated by substitution of the free and bound substrate concentrations, calculated from the rate data. into the Klotz equation describing protein-ligand equilibria, and with values determined nonenzymitally by gel chromatography and difference spectroscopy.
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