Amino acid sequence prerequisites for the formation of cn ions
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- Downard, K.M. & Biemann, K. J Am Soc Mass Spectrom (1993) 4: 874. doi:10.1016/1044-0305(93)87005-W
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Ammo acid sequence prerequisites are described for the formation of c, ions observed in high-energy collision-induced decomposition spectra of peptides. It is shown that the formation of cn ions is promoted by the nature of the amino acid C-terminal to the cleavage site. A propensity for cn cleavage preceding threonine, and to a lesser extent tryptophan, lysine, and serine, is demonstrated where fragmentation is directed N-terminally at these residues. In addition, the nature of the residue N-terminal to the cleavage site is shown to have little effect on cn ion formation. A mechanism for cn ion formation is proposed and its applicability to the results observed is discussed.