Modulation of the behavior of a protein in polyacrylamide gel electrophoresis in the presence of dodecyl sulfate by varying the cations.

The denaturation of Aspergillus oryzae alpha-amylase by dodecyl sulfates can be modulated by the change of cations among sodium, lithium, and several alkanolammonium ions. The denaturation can be detected by polyacrylamide gel electrophoresis in the presence of alkanolammonium dodecyl sulfates, particularly around 0 degree C where the denaturation reaction can be virtually frozen. The moderate stability of the amylase against denaturation by dodecyl sulfates helped to demonstrate the difference among the cations. We previously reported a significant difference among the dodecyl sulfates in their ability to dissociate chlorophyll-protein assemblies. The present results indicated that there is also a difference in the ability of the dodecyl sulfates to denature the amylase, a monomeric water-soluble protein. Two species, one retaining intact disulfide bonds and the other underwent a single sulfhydryl-disulfide exchange reaction, were generated during amylase denaturation by dodecyl sulfates.