The Staphylococcal Phosphoenolpyruvate‐Dependent Phosphotransferase System

Abstract

The galactoside-specific membrane-bound component of the staphylococcal phosphoenolpyruvate-dependent phosphotransferase system, enzyme IIlac, was purified to homogeneity. The purification procedure involved several extractions steps at the particulate state, followed by solubilization with Triton X-100. Up to this stage the biological activity of enzyme II was preserved. Isolation of the homogeneous protein involved gel filtration of the dodecylsulfate-denatured material. An apparent MW of the polypeptide chain was estimated by dodecylsulfate gel electrophoresis. The 55,000 MW protein is visible in dodecylsulfate gels upon induction of the staphylococcal lac operon as a more intensively stained area. Antibodies against the denatured 55,000 MW protein inhibit the mutant complementation assay of enzyme II offered as membrane fragments. This demonstrates that the 55,000 MW protein and enzyme IIlac are identical. Polarity and the solubility of the protein in detergents are typical for an integral membrane protein.