Comparison of CID, ETD and metastable atom-activated dissociation (MAD) of doubly and triply charged phosphorylated tau peptides.
The fragmentation behavior of the 2+ and 3+ charge states of eleven different phosphorylated tau peptides was studied using collision-induced dissociation (CID), electron transfer dissociation (ETD) and metastable atom-activated dissociation (MAD). The synthetic peptides studied contain up to two known phosphorylation sites on serine or threonine residues, at least two basic residues, and between four and eight potential sites of phosphorylation. CID produced mainly b-/y-type ions with abundant neutral losses of the phosphorylation modification. ETD produced c-/z-type ions in highest abundance but also showed numerous y-type ions at a frequency about 50% that of the z-type ions. The major peaks observed in the ETD spectra correspond to the charge-reduced product ions and small neutral losses from the charge-reduced peaks. ETD of the 2+ charge state of each peptide generally produced fewer backbone cleavages than the 3+ charge state, consistent with previous reports. Regardless of charge state, MAD achieved more extensive backbone cleavage than CID or ETD, while retaining the modification(s) in most cases. In all but one case, unambiguous modification site determination was achieved with MAD. MAD produced 15-20% better sequence coverage than CID and ETD for both the 2+ and 3+ charge states and very different fragmentation products indicating that the mechanism of fragmentation in MAD is unique and complementary to CID and ETD.
Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701-2979, USA.
Shannon L
SL
Cook
Carolyn M
CM
Zimmermann
David
D
Singer
Maria
M
Fedorova
Ralf
R
Hoffmann
Glen P
GP
Jackson
D000595:Amino Acid Sequence; D007477:Ions / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D008969:Molecular Sequence Data; D010748:Phosphopeptides / Q000737:chemistry*; D017422:Sequence Analysis, DNA / Q000379:methods*; D016875:tau Proteins / Q000737:chemistry*
D007477:Ions; D010748:Phosphopeptides; D016875:tau Proteins