Formaldehyde-hydrochloric acid treatment. A fluorescence histochemical method for the demonstration of tryptophan residues in peptides and proteins.

Treatment with formaldehyde gas and HCl vapor, simultaneously or in sequence, induces fluorescence with indoles, including tryptophan residues of peptides, as is evident from studies on protein droplet models. Among cells that display intense formaldehyde-HCl-induced fluorescence are pancreatic exocrine cells, gastric chief cells, Paneth cells and… CONTINUE READING