A Review on the Effects of Supercritical Carbon Dioxide on Enzyme Activity

Abstract

Different types of enzymes such as lipases, several phosphatases, dehydrogenases, oxidases, amylases and others are well suited for the reactions in SC-CO2. The stability and the activity of enzymes exposed to carbon dioxide under high pressure depend on enzyme species, water content in the solution and on the pressure and temperature of the reaction system. The three-dimensional structure of enzymes may be significantly altered under extreme conditions, causing their denaturation and consequent loss of activity. If the conditions are less adverse, the protein structure may be largely retained. Minor structural changes may induce an alternative active protein state with altered enzyme activity, specificity and stability.

Enzymatic activity and conformational and morphological studies of four commercial lipases treated with supercritical carbon dioxide

“…One of the most important is the amount of water needed to maintain their native conformation and hence, their functionality. During exposure to SC-CO 2 essential water of the enzyme can be solubilized into the SC-CO 2 (0.3 to 0.5 g water/100 g CO 2 , depending on operating pressure and temperature [7]). During the depressurization step, CO 2 is released and the solubilized water is removed from the enzyme preparation.…”

“…In high pressure-batch stirred reactors, exposure time, depressurization rate, and the number of pressurization/depressurization cycles are also important parameters that must be considered [7].…”

Inactivation of Aspergillus Spores in Clinical Wastes by Supercritical Carbon Dioxide

“…Thus, the fungi failed to grow even in the presence the enrichment component such as skim milk. In previous study, Fadiloglu and Erkmen [56] showed that 84 % of the initial activity of lipase was lost after exposed for CO 2 under atmospheric pressure at initial pH 7.15 and 50 • C, while still stable in the absence of CO 2 even at 50 • C. Wimmer and Zarevúcka [57] revealed that the activity of catalase, polyphenol oxidase and peroxidase reduced by SC-CO 2 (20 MPa and 35 • C). Leitgeb et al [58] revealed that the SC-CO 2 led to inactivation of cellulase and amylase enzymes produced from Hortaea werneckii.…”

Deactivation of isoamylase and β-amylase in the agitated reactor under supercritical carbon dioxide

“…Earlier studies suggested that SC-CO 2 serves as a superior reaction environment for enzyme hydrolysis [22]. Previously, two starch-degrading enzymes, a-amylase and glucoamylase, were demonstrated to be active in a SC-CO 2 medium [23].…”