Preparation And Transesterification Activity Of Protease-AOT Ion Pair In Non-aqueous Phase System

New function materials of textile is an important direction of research nowadays. The composite and modification on cotton to the preparation of new function fiber is one of the hottest. Because the catalytic activity of some enzymes is reversible, the transesterification between alcohols and esters can be catalyzed when enzymes in a specific environment (such as non-aqueous phase system), which provides a new way for cotton fiber processing.This paper investigated the method of determining the content of AOT (Dioctyl sodium sulfonated succinate). Then used AOT to extract bacillolysin (EC 3.4.24.28) into organic phase via surfactant-enzyme ion pair. The factors affecting the ion pair formation were investigated. The structure of enzyme before and after extraction was observed by CD spectroscopy. After extraction the transesterification activity was measured.The results indicated that 10 min was required for AOT and R-6G (Rhodamine 6G)to react and 9 h was needed for toluene to extract. In the preparing of ion pair, the results proved that magnetic stirring at 120 rpm for 6 h was better than other mixing methods. The initial pH of the aqueous phase affected both formation of enzyme-surfactant ion pair and transfer of the enzyme into the solvent. The optimal pH was about 5.0. Addition of CaCl2 could partially prevent emulsifying during mixing, but excessive CaCl2 could negatively affected the formation of ion pair and transfer of the enzyme from aqueous phase into solvent. The transferred amount of enzyme into the solvent increased when AOT concentration was increased, although the initial concentration of the enzyme in the aqueous was kept constant. However, with a constant AOT in the solvent, the enzyme transfer increased with the increasing of the initial concentration of the enzyme in the aqueous first but decreased then with further increasing. The enzyme structure has not changed a lot after extaction. Results showed that enzyme extracted into the organic phase was still active and could catalyze the transesterification. The research showed ion pair had the character of "pH memory" .The organic solvents can impact the activity strongly. The transesterification activity of enzyme in toluene, isooctane and pyridine has been investigated.