193 nm photodissociation of larger multiply-charged biomolecules

In contrast to most ion dissociation methods, 193 nm ultraviolet photodissociation of electrosprayed melittin (2.8 kDa) and ubiquitin (8.6 kDa) molecular ions yields new c and z ions (backbone amine bond dissociation) that provide additional sequence information. Dissociation by collisions or infrared photons produce b and y ions; for cleavages between the same amino acids the c ion represents the addition of NH2 to the b ion, and z the loss of NH2 from the y ion, so that these ions can be differentiated by this ± 16.02 Da difference. However, 193 nm photodissociation of 12–29 kDa ions as yet does not give collectable product ions, and that of the very stable y18²⁺ ion from ubiquitin only effects a side chain loss. 193 nm irradiation of negative ions of all-T 30-mer DNA appears to eject electrons; apparently this is the first observation of electron photodetachment from multiply-charged negative ions. © 1995, Elsevier Science B.V. All rights reserved. All rights reserved.

Duke Scholars

Author Ziqiang Guan Biochemistry