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  • Title: Mechanism of adaptation of an atypical alkaline p-nitrophenyl phosphatase from the archaeon Halobacterium salinarum at low-water environments.
    Author: Marhuenda-Egea FC, Piera-Velázquez S, Cadenas C, Cadenas E.
    Journal: Biotechnol Bioeng; 2002 Jun 05; 78(5):497-502. PubMed ID: 12115118.
    Abstract:
    Enzymes suspended in organic solvents represent a versatile system for studying the involvement of water in catalytic properties and their flexibility in adapting to different environmental conditions. The extremely halophilic alkaline p-nitrophenylphosphate phosphatase from the archaeon Halobacterium salinarum was solubilized in an organic medium consisting of reversed micelles of hexadecyltrimethylammoniumbromide in cyclohexane, with 1-butanol as cosurfactant. Hydrolysis of p-nitrophenylphosphate was nonlinear with time when the enzyme was microinjected into reversed micelles that contained substrate. These data are consistent with a kinetic model in which the enzyme is irreversibly converted from an initial form to a final stable form during the first seconds of the encapsulation process. The model features a rate constant (k) for that transition and separate hydrolysis rates, v(1) and v(2), for the two forms of the enzyme. The enzyme conversion may be governed by the encapsulation process.
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