DNA-SEQUENCING WITH BLACKBODY INFRARED RADIATIVE DISSOCIATION OF ELECTROSPRAYED IONS

As shown by Williams for positive multiply-charged ions, negative elec trosprayed ions trapped in a Fourier-transform ion cyclotron resonance mass spectrometer can be dissociated efficiently with BIRD. For a 50- mer DNA, an ion cell wall temperature of 90 degrees C gives no dissoci ation and 120 degrees C gives only uninformative base loss. However, 1 50 degrees C gives extensive dissociation producing ionic products qua litatively similar to those from laser IR, collisionally activated, an d nozzle-skimmer dissociation. Under the conditions used, BIRD produce s more fragment ions that have lost an additional base (AH). Structura lly informative BIRD spectra are also observed for a 100-mer DNA and a double-strand 64-mer DNA. For both samples, BIRD successfully 'boiled off' non-covalent adducts that produced an uninterpretable spectrum, while laser IR was only successful in this for the ds 64-mer. (C) 1997 Elsevier Science B.V.