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Mechanism of adaptation of an atypical alkaline p ‐nitrophenyl phosphatase from the archaeon Halobacterium salinarum at low‐water environments
Author(s) -
MarhuendaEgea Frutos C.,
PieraVelázquez Sonsoles,
Cadenas Chiquinquirá,
Cadenas Eduardo
Publication year - 2002
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.10216
Subject(s) - halobacterium salinarum , micelle , chemistry , hydrolysis , alkaline phosphatase , enzyme , cyclohexane , organic chemistry , biochemistry , bacteriorhodopsin , membrane , aqueous solution
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. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 497–502, 2002.