Mechanism of adaptation of an atypical alkaline p-nitrophenyl phosphatase from the archaeon Halobacterium salinarum at low-water environments.
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.
Marhuenda-Egea
Frutos C
FC
División de Bioquímica, Facultad de Ciencias, Universidad de Alicante, Aptdo. 99, 03080 Alicante, Spain. frutos@ua.es
Piera-Velázquez
Sonsoles
S
Cadenas
Chiquinquirá
C
Cadenas
Eduardo
E
D000064:Acclimatization; D000469:Alkaline Phosphatase / Q000096:biosynthesis* / Q000737:chemistry*; D017753:Ecosystem; D005246:Feedback; D019617:Halobacterium salinarum / Q000201:enzymology*; D006868:Hydrolysis; D008823:Micelles; D008956:Models, Chemical; D009596:Nitrophenols / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000737:chemistry*; D012680:Sensitivity and Specificity; D014867:Water / Q000737:chemistry*
D008823:Micelles; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D014867:Water; C008644:nitrophenylphosphate; D000469:Alkaline Phosphatase