Detailed Explanation
C-terminal fragment ion produced during peptide fragmentation in tandem mass spectrometry (MS/MS). When a peptide bond breaks during collision-induced dissociation (CID) in the mass spectrometer, each cleavage generates two fragments: a b-ion (retaining the N-terminus with the charge on the carbonyl) and a y-ion (retaining the C-terminus with the charge on the amino group + one proton).
A complete series of y-ions (y₁, y₂, y₃... from the C-terminus) allows reading the peptide sequence backward, while b-ions read it forward. Together, b-ion and y-ion series provide complementary sequence information for unambiguous peptide identification. De novo sequencing (determining sequence without a database) relies on mass differences between consecutive y-ions or b-ions, each corresponding to a specific amino acid residue mass.
Key Facts
- C-terminal fragment ion produced during peptide fragmentation in tandem mass spectrometry (MS/MS).
- When a peptide bond breaks during collision-induced dissociation (CID) in the mass spectrometer, each cleavage generates two fragments: a b-ion (retaining the N-terminus with the charge on the carbonyl) and a y-ion (retaining the C-terminus with the charge on the amino group + one proton).
- A complete series of y-ions (y₁, y₂, y₃... from the C-terminus) allows reading the peptide sequence backward, while b-ions read it forward.
- Together, b-ion and y-ion series provide complementary sequence information for unambiguous peptide identification.
- De novo sequencing (determining sequence without a database) relies on mass differences between consecutive y-ions or b-ions, each corresponding to a specific amino acid residue mass.
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