Comparison of lipase-catalysed esterification in supercritical carbon dioxide and in n-hexane

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

“…A slightly decrease in lipase activity has been found by increasing the number of pressurization/depressurization cycles from 1 to 3 (from 92.1 to 88.1 % initial activity for Lipozyme RM IM and from 82.2 to 78.8 % initial activity for Lipozyme 435). These results are in agreement with Marty et al [27] that reported activity loss in the lipase from Mucor miehei treated with hydrated SC-CO 2 and no further activity loss in successive depressurizations using dry SC-CO 2 . It has been also reported that hydrolases with disulfide bonds have a lower degree of inactivation after several pressurization/depressurization cycles that enzymes without them [28].…”

Enzymatic catalysis in cosolvent modified pressurized organic solvents

“…These results suggest that the esterification rate is approximately an order of magnitude higher in SCF ethane than in pressurized hexane at identical reaction conditions over the range of variables investigated. Similar rate enhancements have been observed for enzymatic esterifications in SCF CO 2 relative to unpressurized hexane (Marty et al, 1990;Nakamura et al, 1990). …”

“…The rate and selectivity of enzymatic reactions in organic solvents may be directly affected by solvent strength (Chaudhary et al, 1996) or influenced by indirect measures of solvent strength including thermodynamic water activity (a w ) and the solubility of the substrate (e.g., Kamat et al, 1993;Martins et al, 1992;Marty et al, 1990;Rantakylä and Aaltonen, 1994;Valivety et al, 1991). Enzymatic catalysis in SCFs exploits the ability to dramatically alter solvent strength with small changes in temperature and pressure in the near-critical region.…”

Reactions at supercritical conditions: Applications and fundamentals

“…This extensive research into these systems has identified and elucidated the effects of many of the important variables, such as pressure (Miller et al, 1990(Miller et al, , 1991Erickson et al, 1990;Ikushima et al, 1993). Reaction rates in SC CO, and in organic solvents (typically hexane) have been compared (Martins et al, 1991;Bolz et al, 1991;Marty et al, 1990Marty et al, , 1992aKamat et al, 1992Kamat et al, , 1993Chi et al, 1988;Pasta et al, 1989). Kinetics parameters and reaction mechanisms have been reported (Miller et al, 1991;Bolz et al, 1991;Marty et al, 1992b;Dumont et al, 1992).…”