Abstract: In this study, a method for the extraction and purification of actin from Siniperca chuatsi myofibrillar protein by alcohol-inorganic salt aqueous two-phase systems was established. A new method for the quantitative detection of S. chuatsi actin was explored using high performance micellar electrokinetic capillary chromatography (MECC) with diode array detection (DAD). The results showed that an isopropanol/ammonium sulfate aqueous two-phase system was determined as the optimal separation system by actin purity detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and extraction efficiency. Using combination of one-factor-at-a-time method and response surface methodology, the optimal aqueous two-phase system was determined to be composed of 26% isopropanol and 11% ammonium sulfate at pH 9.0, giving an actin extraction yield of 11.04%, which was close to the predicted value of the model. The actin peak occurred at around 10 minutes in the capillary electrophoresis spectrum, whose baseline was smooth without any noise peak. The results from this study lay an experimental foundation for the identification of quality attributes of precious fish and for development of fish actin standard products, and also provide a theoretical basis for the development and utilization of fish protein functions and rapidquantitative detection of fish proteins.

Key words: Siniperca chuatsi, aqueous two-phase system, actin extraction, capillary electrophoresis, response surface methodology