Positive cooperativity in substrate binding of human prostatic acid phosphatase entrapped in AOT–isooctane–water reverse micelles
| Autor: | Ewa Luchter-Wasylewska, Małgorzata Iciek |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Male
Acid Phosphatase Cooperativity positive cooperativity Medicinal chemistry Micelle Substrate Specificity Enzyme catalysis Biomaterials AOT-isooctane-water reverse micelles Hydrolysis Colloid and Surface Chemistry phenyl phosphate enzyme kinetics monomer-dimer-tetramer equilibrium dissociation/association Humans Enzyme kinetics Aqueous solution Chromatography biology hill equation Chemistry Acid phosphatase Cooperative binding Surfaces Coatings and Films Electronic Optical and Magnetic Materials active subunit Kinetics 1-naphthylphosphate human prostatic acid phosphatase biology.protein Protein Tyrosine Phosphatases |
| Zdroj: | Journal of Colloid and Interface Science. 273:632-637 |
| ISSN: | 0021-9797 |
| Popis: | The kinetics of 1-naphthyl phosphate and phenyl phosphate hydrolysis, catalyzed by human prostatic acid phosphatase (PAP) entrapped in AOT–isooctane–water reverse micelles, has been studied over surfactant hydration degree (w0) range 5 to 35. Continuous spectrophotometric acid phosphatase assays, previously prepared, were employed. PAP was catalytically active over the whole w0 studied range. In order to determine steady-state reaction constants the experimental data were fitted to Hill rate equation. Positive cooperativity in substrate binding was observed, as it was earlier found in aqueous solutions. The extent of cooperativity (expressed as the value of the Hill cooperation coefficient h) increased from 1 to 4, when the micellar water-pool size was growing, at fixed enzyme concentration. In the plots of catalytic activity (kcat) versus w0, the maxima have been found at w0=10 (pH 5.6) and 23 (pH 3.8). It is suggested that catalytically active monomeric and dimeric PAP forms are entrapped in reverse micelles of w0=10 and 23, respectively. |
| Databáze: | OpenAIRE |
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