PNNL

Abstract

In this work we demonstrate the use of peptide as a stable internal mass standard to obtain accurate mass measurements of infrared multiphoton dissociation (IRMPD) generated phosphorothioate oligonucleotide fragment ions. Because oligonucleotides are more readily dissociated in the gas phase by IRMPD than are proteins or peptides, the duration and power of the IRMPD event can be set above the oligonucleotide dissociation threshold without inducing fragmentation of the internal peptide standard. This conept is illustrated with electrospray ionization fourier transform ion cyclotron resonance IRMPD of a 20-mer phosphorothioate olgonucleotide in the presence of a small amount of insulin a-chain.