The direct hydrolysis of proteins containing tryptophanon polyvinylidene difluoride membranes by mercaptoethanesulfonic acid in the vapor phase

Abstract A procedure for the amino acid analysis of polypeptides that contain tryptophan on polyvinylidene difluoride membranes is described. Lysozyme, carbonic anhydrase, phytochrome, and ovalbumin were tested. The protein, which was separated from others by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, was blotted from the gel onto a polyvinylidene difluoride membrane and directly hydrolyzed by 3 n aptoethanesulfonic acid vapor in a vacuum at 176°C for 25 min. The hydrolysate was extracted with 0.1 n HCl and 30% methanol and used for amino acid analysis. The tested proteins were adequately hydrolyzed, and the recovery of tryptophan was very efficient.