Amino-terminal analysis of polypeptide using dimethylaminoazobenzene isothiocyanate

A new method for qualitative and quantitative N-terminal analysis of polypeptide using dimethylaminoazobenzene-isothiocyanate is presented. The method can recover all naturally occurring N-terminal amino acids, including asparagine, glutamine, and tryptophane in a nearly quantitative yield. Less than 1 nmol of polypeptide is required for qualitative N-terminal analysis and 5 to 10 nmol of polypeptide is used for quantitative N-terminal analysis. Applications and expected limitations of this new N-terminal method are described.