Identification of covalently bound fatty acids on acylated proteins immobilized on nitrocellulose paper

A general method for identification of fatty acids covalently bound to acylated proteins following their electrophoretic transfer onto nitrocellulose paper is described. As demonstrated for [3H]palmitoylated RAS1 protein of Saccharomyces cerevisiae and the acylated acyl carrier protein of Spirodela oligorrhiza, this procedure alleviates the need for elution of proteins from polyacrylamide gel slices. Fatty acid ligands of such proteins are hydrolyzed directly from their immobilized state on the nitrocellulose paper, then derivatized with p-nitrophenacyl bromide, and finally resolved by reversed-phase high-performance liquid chromatography. The amount of acylated protein required for identification of acyl groups is minimized compared to that required for more conventional approaches by coupling a radioactive flow detector with the HPLC system.