Enzymatic dipeptide synthesis by surfactant-coated α-chymotrypsin complexes in supercritical carbon dioxide

Enzymatic dipeptide synthesis by surfactant-coated a-chymotrypsin complexes was performed in supercritical CO2 and liquid CO2 at 308.2 and 333.2 K at pressures of 6.1 and 10.1 MPa. The enzymatic activity of coated alpha-chymotrypsin complexes for dipeptides synthesis at 10.1 MPa in supercritical CO2 (SC-CO2) was higher than that in a liquid CO2 and ethyl acetate solution at 6.1 MPa. The behavior of alpha-chymotrypsin in SC-CO2 was similar to that in liquid ethyl acetate. And increasing the pressure and temperature increased the maximum conversion and the enzymatic reaction rate in SC-CO2. Furthermore, the control of the water content in the reaction media had a dominant effect on the enzymatic activity. The maximum conversion for the dipeptide synthesis by the surfactant-coated alpha-chymotrypsin was obtained at 4% water content. The alpha-chymotrypsin complexes exhibited a higher enzymatic activity than native alpha-chymotrypsin in SC-CO2. The nonionic surfactants L-glutamic acid dialkyl ester ribitol amide and sorbitan monostearate were more favored than the anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate.