Photoaffinity labelling with the cytokinin agonist azido-CPPU of a 34 kDa peptide of the intracellular pathogenesis-related protein family in the moss Physcomitrella patens
A fluorographic procedure was optimized which utilized acetic acid as the solvent for 2,5-diphenyloxazole (PPO). This procedure was then compared with existing fluorographic procedures which utilize PPO in dimethyl sulphoxide or sodium salicylate in water, and a commercially available fluorographic solution. En3Hance (New England Nuclear Corp.). A comparison of the four methods revealed that all of the procedures resulted in essentially the same efficiency of radioactivity detection. The acetic acid/PPO procedure was found to have several technical advantages. There is no need to pre-fix proteins in gels, and either agarose or acrylamide gels can be used. The acetic acid/PPO procedure was found to be a simple, sensitive and efficient alternative fluorographic method.