Identification of surface proteins of a bacterial membrane using thiolactone-activated polyacrylamide beads

A new method for the determination of protein accessibility in membranes and membrane fractions using a resin, 'Enzacryl' polythiolactone, is described. Enzacryl polythiolactone is a hydrophilic polymer of acrylamide and acrylamide derivatives with thiolactone ring substituents. The binding of enzymes and proteins to this resin is accomplished very simply by mixing them together in a simple aqueous buffer. Groups which react with the polymer in the pH range 5--9 include aliphatic and phenolic hydroxyls and aliphatic amino groups. Surface proteins of Bacillus licheniformis membrane and solubilised membrane fractions are bound irreversibly to this resin. Inaccessible proteins remaining in the fractions are solubilised with sodium dodecyl sulphate and examined by sodium dodecyl sulphate polyacrylamide gel electrophoresis.