If low MS/MS identification rates are observed without clear indications of origin (e.g. intensities are high, samples are mass-calibrated, etc) it might be beneficial to re-run MaxQuant allowing more variable modifications, e.g.
- carbamylation (N-Term, lysine), due to improper denaturing conditions using urea (temp, freshness)
- deamidation (asp, glu), due to prolonged digestion at mildly basic pH
To see the impact of these mods (beside the overall number of identified peptides/proteins after FDR), a Pareto chart (barchart) of modifications will be useful.
If low MS/MS identification rates are observed without clear indications of origin (e.g. intensities are high, samples are mass-calibrated, etc) it might be beneficial to re-run MaxQuant allowing more variable modifications, e.g.
To see the impact of these mods (beside the overall number of identified peptides/proteins after FDR), a Pareto chart (barchart) of modifications will be useful.