Dynorphin A(1–8) in human placenta: Amino acid sequence determined by tandem mass spectrometry

Abstract Presence of the κ receptor-preferring neuropeptide dynorphin A(1–8) in human placenta has been demonstrated by mass spectrometry to establish rigorously the appropriate molecular weight and amino acid sequence. Liquid secondary ionization mass spectrometry produced the protonated molecule ion, (M + H) + , at m z 981 of the endogenous peptide, and tandem mass spectrometry collected the product ion spectrum that contained the appropriate amino acid sequence-determining fragment ions produced from the precursor ion (M + H) + . The amino acid sequence of the peptide is YGGFLRRI.