Use of electrospray ionization mass spectrometry to probe antisense peptide interactions

Electrospray ionization mass spectrometry with a magnetic sector instrument has been used to test for non-covalent interactions between human angiotensin II (M(r) 1046) and eight synthetic octapeptides that are considered complementary peptides (encoded by DNA sequences complementary to the DNA sequence that codes for human angiotensin II) or analogues of these antisense peptides. The relative abundance of the doubly charged heterodimer complex broadly correlates to the trend observed with solution-phase studies such as 1H nuclear magnetic resonance. Dissociation constants for the reaction in solution are in the high micromolar range. Electrospray ionization can potentially be a sensitive method for rapidly screening weak molecular interactions. Further work is necessary to study the possible gas-phase contributions to the observed binding interactions indicated in the mass spectrometry data.