Collision-Induced Dissociations of Deprotonated Peptides. Dipeptides Containing Asn, Arg and Lys

Abstract

The presence and position of Asn, Arg and Lys residues in dipeptides may be determined from a consideration of the collisional activation mass spectra of the (M-H)- ions formed by fast atom bombardment. All spectra show the basic dipeptide cleavage, i.e. NH2CH(R1)CONHCH(R2)CO2- → NH2C(R1)CONHCH(R2)CO2H → NH2C(R1)=C=O + -NHCH(R2)CO2H. There are a number of fragmentations characteristic of a particular α side chain: for example, Arg loses HN=C=NH (42 u).