USE OF ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY TO PROBE ANTISENSE PEPTIDE INTERACTIONS

Electrospray ionization mass spectrometry with a magnetic sector instr ument has been used to test for noncovalent interactions between human angiotensin II (M, 1046) and eight synthetic octapeptides that are co nsidered complementary peptides (encoded by DNA sequences complementar y to the DNA sequence that codes for human angiotensin II) or analogue s of these antisense peptides. The relative abundance of the doubly ch arged heterodimer complex broadly correlates to the trend observed wit h solution-phase studies such as H-1 nuclear magnetic resonance. Disso ciation constants for the reaction in solution are in the high micromo lar range. Electrospray ionization can potentially be a sensitive meth od for rapidly screening weak molecular interactions. Further work is necessary to study the possible gas-phase contributions to the observe d binding interactions indicated in the mass spectrometry data.