Stability of an extreme halophilic alkaline phosphatase from Halobacteriumsalinarium in non-conventional medium

Alkaline p-nitrophenylphosphate phosphatase from the halophilic archaeon Ha lobacterium salinarum (earlier halobium) was solubilised in organic medium using reversed micelles of hexadecyltrimethylammonium bromide in cyclohexan e, with I-butanol as co-surfactant. The stability of alkaline p-nitrophenyl phosphate phosphatase in this system was studied at different conditions, w (u) (H2O/[surfactant]), salt concentration, with and without M (+2). At all the conditions assayed, alkaline p-nitrophenylphosphate phosphatase was mo re stable in reversed micelles than in bulk aqueous solution (at 25 degrees C). The stabilisation effect of the reversed micelles was dramatic when the enzyme was dialysed against Mn (+2)-free buffer since the enzyme lost all the activity within 90 min in aqueous medium, but it retained approximately 72% of the initial enzymatic activity for 90 min in reversed micelles. (C) 2001 Elsevier Science B.V. All rights reserved.