Protein pico-sequencing with 4-([5-(dimethylamino)-1-naphthylsulfonyl]amino) phenyl isothiocyanate

A novel manual liquid phase protein sequencing method using the fluorescent reagent, 4-([5-(dimethylamino)-1-naphthylsulfonyl] amino) phenyl isothiocyanate proposed by Jin et al. (FEBS Lett. 198, 150, 1986) has been established. This method allowed sequence determination using 100 pmol and 1 nmol of insulin B chain (oxidised) for 9 and 19 cycles respectively with thin-layer chromatographic identification of the fluorescent thiohydantoin amino-acid derivatives. The method compares favorably in sensitivity with other conventional manual protein sequencing methods.