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Published on: May 15, 2015
Enhancement of enzyme activity in supercritical carbon dioxide via changes in acid-base conditions
Neil Harper1, Susana Barreiros
1REQUIMTE/CQFB, Departamento de Química, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal. nharper_pt@yahoo.co.uk
Abstract:
Enzyme performance is often impaired in supercritical carbon dioxide. We were able to enhance enzyme activity in this medium via changes in acid-base conditions by using ion-exchange materials (solid H(+)/Na(+) buffer pairs and a zeolite), which were selected on the basis of the response of an organosoluble acid-base indicator. The concentration of ion-exchange materials had an important effect on the catalytic activity of subtilisin Carlsberg cross-linked enzyme crystals (CLECs), and this was related to the protonation and hydration states of the enzyme. The buffer Na(2)CO(3)/NaHCO(3) gave the highest enhancement in enzyme activity (by a factor of 54), probably as a result of its high basicity and capacity to counteract the deleterious effect of carbonic acid to a greater extent than the other materials tested.
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