Effect of cosurfactant on extraction and activity of alpha-chymotrypsin in NaDEHP microemulsion

Abstract

Liquid-liquid extraction using microemulsion has gined increasing interest from various industries for its potential applications in the separation and purification of biomolecules such as proteins and antibiotics. In this research, the extraction and activity of a-chymotrypsin using two different microemulsion systems of sodium bis (2-ethylhexyl) phosphate (NaDEHP)/isooctance/brine were studied with an emphasis on the effect of cosurfactant. Two cosurfactants used in this study were tributylphosphate (TBP) and bile salt cosurfactant, 3-[(3-cholamidyl-propyl)dimethyl ammonio]-1-propanesulfonate (CHAPS). At near neutral pH and low salt concentration, an extraction efficiency of more than 70% was obtained using the microemulsion with TBP as a cosufactant whereas only about 30% was achieved in the system with CHAPS as a cousurfactant. Subsequent recovery of the extracted protein using divalent metal ions showed that almost 75% of extracted protein in system with TBP could be recovered and approximately 4% was recovered from the system with CHAPS. The enzymatic activities of the recovered proteins from these two systems were compared to fresh protein and found to be quite different. The protein recovered from the NaDEHP system with CHAPS as a cosurfactant was shown to retain approximately twice activity than that of the system with TBP as a cosurfactant