On the origin of unchanged lipase activity profile in cationic reverse micelles

Das, Prasanta Kumar ; Chaudhuri, Arabinda (2000) On the origin of unchanged lipase activity profile in cationic reverse micelles Langmuir, 16 (1). pp. 76-80. ISSN 0743-7463

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Official URL: http://pubs.acs.org/doi/abs/10.1021/la990366t

Related URL: http://dx.doi.org/10.1021/la990366t

Abstract

The results of the present investigation demonstrate that the interfacial regions of cetyltrimethylammonium bromide (CTAB)/isooctane/1-hexanol/water cationic reverse micelles are densely populated by bromide counterions (3.7-2.5 M) and cosurfactant (8.1-6.4 M) across W0 (the mole ratio of water to surfactant)=12-44 and the interfacial concentrations remain grossly unchanged in the presence of a catalytic amount of interfacially solubilized lipase at both pH 6.0 and 7.0 (pH refers to the pH of the aqueous buffer solutions used in preparing the reverse micellar solutions). Both the second-order rate constants k2 and the equilibrium yields for the lipase catalyzed hydrolysis of p-nitrophenylcaproate were also found to be essentially unchanged across the entire range of W0. Our results throw new insight into the origin of such constant second-order rate constants and equilibrium yields for lipase-catalyzed interfacial hydrolysis reactions in cationic reverse micelles across W0=12-44. To our knowledge, the work delineated herein provides the first experimental evidence consistent with grossly unchanged interfacial compositions as the origin for the unchanged activity profiles and the equilibrium yields for lipase-catalyzed reactions in cationic reverse micelles across a wide range of W0.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:8020
Deposited On:25 Oct 2010 09:52
Last Modified:31 Jan 2011 09:12

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