[12] Dansyl chloride procedure

This chapter discusses the formation and stability of dansyl chloride procedure. Dansyl chloride is used for providing fluorescent “handles” for the study of proteins. The reaction of the dye with α-chymotrypsin led them to propose its use as a means of studying the α-amino and other reactive groups of proteins and peptides. It is useful in determining the amino acid sequences of small amounts of peptides. Dansyl chloride is a typical aromatic sulfonyl chloride, and reacts with a wide variety of bases, forming derivatives of differing stabilities. Some recommended procedure for peptides discussed are (1) reagents, buffers, and marker mixtures, (2) labeling of peptide, (3) hydrolysis, (4) visualization of compounds on paper, and (5) interpretation of results. The increased requirement for dansyl chloride brings with it the necessity for removing the large amounts of DNS-OH formed by its hydrolysis. The removal procedures used are labeling, removal of salt, urea, DNS-OH, hydrolysis, and identification of end groups. Some of the advantages and limitations of the method are mentioned. The main advantage is the ease and rapidity with which end groups may be determined on very small amounts of peptides.