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Posted by Ville Koskinen (August 19, 2020)

Validating intact crosslinked peptide matches

Intact crosslinked search results are more complex than conventional (non-crosslinked) searches, because there are many more degrees of freedom. The precursor mass could be within tolerance of a looplinked sequence, a linear sequence with monolink and several different alpha-beta candidates. Each possibility is multiplied if you also consider variable modifications like oxidation of methionine. Mascot 2.7 uses the same scoring [...]

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Posted by John Cottrell (November 15, 2018)

The plus one dilemma

There are several common modifications that can add approximately 1 Da to a peptide mass. Even if you have high accuracy data, it can sometimes be difficult to figure out which one is correct.   Delta Lys->Glu substitution 0.947630 Leu->Asn or Ile->Asn substitution 0.958863 Deamidation at N or Asn->Asp substitution 0.984016 Deamidation at Q or Gln->Glu substitution 0.984016 Citrullination at [...]

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