Effects of Single Amino Acid Substitution on the Dissociation of Multiply Charged Multiprotein Complexes in the Gas Phase

The effects of amino acid substitutions on the product ion charge distributions for protonated and deprotonated homogeneous and heterogeneous multiprotein complexes in the gas phase are studied using Fourier-transform mass spectrometry and the blackbody infrared radiative dissociation technique. Notably, it is shown that a single amino acid substitution in the leaving subunit can cause a small but measurable change in product ion charge distribution. Evidence that the degree of charge enrichment of the leaving subunit is influenced by the number of strongly basic or acidic residues within the subunit for the protonated and deprotonated complexes, respectively, is reported.