MASS-SPECTROMETRIC CHARACTERIZATION OF AMADORI COMPOUNDS RELATED TO THE OPIOID PEPTIDE MORPHICEPTIN

The high-energy collision-induced dissociation (CID) spectra of synthe sized Amadori compounds, related to the exogenous opioid peptide morph iceptin, have been investigated, The spectra of [M + H](+) ions of pro tected, partially protected and unprotected Amadori compounds exhibit mainly A- and Y''-type sequence ions. The protected compounds show pea ks corresponding to the elimination of a C3H6O molecule, characteristi c of a protecting isopropylidene group at the saccharide moiety, The p osition of the isopropylidene group in the partially protected Amadori compound has been derived from the CID spectrum of its [M + Na](+) io n, A two-bond cross-ring cleavage reaction generates an ion at m/z 656 , corresponding to the loss of a 90 Da neutral (C3H6O3), and must orig inate from the C2-C3 isopropylidene-protected Amadori compound, The mo st intense ions in the CID spectrum of the [M + H](+) ion of the unpro tected Amadori compound arise from losses of water molecules. Comparis on of the CID spectra of the [M + H](+) ions of Amadori compounds with that for the parent peptide morphiceptin revealed a preferential A(1) -ion formation for Amadori compounds. (C) 1998 John Wiley & Sons, Ltd.