Effect of sodium dodecyl sulfate (SDS) denaturant on activity and conformation of alkaline phosphatase from Haliotis diversicolor

The effect of sodium dodecyl sulfate (SDS) on the activity of alkaline phosphatase (ALP) from Haliotis diversicolor has been studied. The results showed that residual activity of the enzyme decreased with increasing SDS concentration.When the concentration of SDS was high to 400 mmol/dm~3, the enzyme activity just lost 33 %. After that, with increasing SDS concentrations, the activity was kept at the level of 67% of the nature enzyme, indicating the enzyme had high endurance to SDS. The effect of SDS on the pH stability of the enzyme was discussed and the results showed that the pH stability range changed from pH 5.9~10.0 to pH 7.6~10.6. The conformational changes of the enzyme in different concentrations of SDS solution were measured by fluorescence absorption spectra and ultraviolet absorption spectra. The fluorescence emission peak (at 335 nm) of the enzyme (hadn’t) shifted sharply. The fluorescence intensity decreased with increasing SDS concentrations at low concentration of SDS and rose back at high concentration of SDS. The ultraviolet absorption peak of the enzyme (hadn’t) shifted sharply, too. It was suggested that the enzyme (molecule) (hadn’t) spread sufficiently, indicating the enzyme conformation was not sensitive to SDS.