Effect of the Asn side chain on the dissociation of deprotonated peptides elucidated by IRMPD spectroscopy

- Non-oxazolone b-type fragments identified for deprotonated peptides.
- b-Type anions from Asn-containing peptides have succinimide structure.
- b2 and b3 anions investigated.
- IR spectroscopy distinguishes between imide and isoimide structures.