A rapid method for acid hydrolysis of protein with a mixture of trifluoroacetic acid and hydrochloric acid.

Proteins have regions which resist hydrolysis with mineral acid. The presence of a strong organic acid was found to be efficient for hydrolysis of a hydrophobic peptide bond. The proposed condition, a 2:1 (by vol.) mixture of concentrated hydrochloric acid and trifluoroacetic acid at 166 degrees C for 25 min was observed to be equivalent to the conventional conditions (6 M HCl at 110 degrees C for more than 24 h) without significant decomposition of amino acids. The method was shown to be superior to the conventional conditions, especially for hydrophobic proteins. The present method destroys tryptophan, as the conventional acid hydrolysis does.