A study on the renaturation of membrane proteins after solubilization in SDS or following polyacrylamide gel electrophoresis in SDS, with special reference to a phosphatase from acholeplasma laidlawii

Abstract

It may be easier to renature SDS-denatured hydrophobic proteins than to renature SDS-denatured water-soluble proteins. This paper presents some support for this hypothesis in the form of literature reports and an experiment of our own with an intrinsic membrane protein (a phosphatase from Acholeplasma laidlawii), that could be completely renatured, to judge from the restored activity, which was equal to (or higher than) that of the untreated enzyme. If this hypothesis is correct it might be possible to devise general methods to reverse the SDS denaturation of hydrophobic membrane proteins. This would be a breakthrough in the purification of at least some membrane proteins, because the high-resolving polyacrylamide gel electrophoresis in SDS could then be used to prepare membrane proteins in a native state. The method used for the renaturation of the SDS-denatured, entirely inactive, phosphatase comprised removal of SDS with the aid of conventional dialysis against a buffer containing the neutral, very efficient and non ultraviolet light-absorbing detergent G3707. For renaturation of the enzyme following an SDS-electrophoresis in polyacrylamide the gel was immersed in the same buffer for several hours; by staining for phosphatase the enzyme could easily be localized in the gel in the form of a yellow band, coinciding with a protein zone.