Table I

SEQUEST filtering criteria used for peptide identification

All ΔCn are required to be ≥0.10.

PeptideCharge stateXcorrTryptic endsOther constraint
Cysteinyl peptidesa1+≥1.5FullyCys
1+≥2.7PartiallyCys
2+≥2.2FullyCys
2+≥3.4PartiallyCys
3+≥2.9FullyCys
3+≥4.1PartiallyCys
N-Linked glycopeptidesb1+≥1.5FullyNX(S/T)
1+≥2.1PartiallyNX(S/T)
2+≥1.8FullyNX(S/T)
2+≥3.3PartiallyNX(S/T)
3+≥2.6FullyNX(S/T)
3+≥4.2PartiallyNX(S/T)
Non-cysteinyl peptides1+≥1.5FullyNone
Non-glycopeptides1+≥3.0PartiallyNone
2+≥2.7FullyNone
2+≥3.7PartiallyNone
3+≥3.3FullyNone
3+≥4.5PartiallyNone
  • a The presence of at least one cysteine residue was required for all peptides.

  • b The presence of at least one NX(S/T) motif was required for all peptides.