Patent ID: 7749769

Claim:
A method of determining amino and carboxy terminal amino acid sequences of a polypeptide, said method comprising introducing said polypeptide into an RF electric field ion containment device, wherein the polypeptide is in a multiply charged cationic state; introducing gas-phase electron transfer reagent anions into said ion containment device; and mixing the introduced electron transfer reagent anions, or derivative electron transfer reagent ions thereof, and the polypeptide, so as to facilitate electron transfer from the electron transfer reagent anions, or derivative electron transfer reagent ions thereof, to the polypeptide, to produce dissociation product cations; introducing gas-phase proton accepting reagent anions into said ion containment device; and mixing the introduced proton accepting reagent anions, or derivative proton accepting reagent ions thereof, and the dissociation product cations, so as to facilitate proton transfer from said dissociation product cations to the proton accepting reagent anions, or derivative proton accepting reagent ions thereof, to reduce the charge on the multiply charged dissociation product cations so the remaining charged c and z-type fragments consist essentially of fragments having four or fewer unit charges, wherein said derivative electron transfer reagent ions and said derivative proton accepting reagent ions are generated within said ion containment device during performance of said method; mass (m/z) analyzing said remaining charged fragments; and determining amino and carboxy sequences of the polypeptide.