SYNTHESIS OF THE PROTEIN-SEQUENCING REAGENT 4-(3-PYRIDINYLMETHYLAMINOCARBOXYPROPYL) PHENYL ISOTHIOCYANATE AND CHARACTERIZATION OF 4-(3-PYRIDINYLMETHYLAMINOCARBOXYPROPYL) PHENYLTHIOHYDANTOINS

We report the synthesis and structural characterization of the novel E dman-type protein-sequencing reagent 4-(3-pyridinylmethylaminocarboxyp ropyl) phenyl isothiocyanate. A panel of thiohydantoins prepared from this reagent were found stable during liquid chromatography-electrospr ay mass spectrometry and were detectable at the low femtomole sensitiv ity level. Furthermore, the signal detected for these compounds in the mass spectrometer was linear from the low femtomole to the low picomo le range. The derivatives showed uv absorbance spectra comparable to t heir phenylthiohydantoin counterparts. The extinction coefficient for the 4-(3-pyridinylmethylaminocarboxypropyl) phenyl thiohydantoin tyros ine was determined by adsorptive sequence analysis of a synthetic pent apeptide featuring an N-terminal I-125-labeled tyrosine. The sequence data suggest that the reagent will be useful for extended sequence ana lysis of proteins and peptides using commercially available gas-liquid -phase sequencers. (C) 1995 Academic Press, Inc.