From: Combinatorial peptidomics: a generic approach for protein expression profiling
 | Depletion approach | Enrichment approach |
---|---|---|
1. Individual steps per each "filtering" stage | 1 step process, i.e. bind to beads (beads discarded) | 3 step process, i.e. bind to beads, wash and elute |
2. Number of combinations using 6 amino acid filters | 63 | 63 |
3. Range of suitable peptide lengths | Longer peptides require less "filtering" stages (i.e. 10 or more amino acid residues preferred) | Shorter peptides require less "filtering" stages (i.e. 10 or less amino acid residues preferred) |
4. Complexity of peptide mixtures | Decreased | Decreased |
5. Amino acid compositional complexity of the remaining peptides | Decreased (by the number of "filters" used) | Not changed (20 amino acids) |
6. Quantitative analysis | A single-stage depletion is more straightforward and quantitative than a triple-stage enrichment | Enrichment approach is less straightforward and robust than the depletion |
7. Scaling up | Possible (larger "filters" or consecutive stages) | Possible (larger "filters" or parallel reactions) |
8. Scaling down | Possible (low fmol level MS sensitivity requires high pmol filter binding capacities) | Especially suitable : low fmol level MS sensitivity requires fmol binding capacities |
9A. Limitations (overloading) | Large binding capacity of the "filters" is crucial – overloading will allow all peptides to pass the "filter" | Overloading of the "filters" is not an issue, excess of sample may be applied |
9A. Limitations (incompletely digestion) | Products of incomplete digestion will be mostly eliminated | Products of incomplete digestion will be mostly retained and may interfere with the downstream purification and analysis steps |
10. Nano-applications | Problematic due to limitation (see above) – excess of binding sites required to maintain efficient separation. Suitable for micro-fluidic applications | Suitable for nano-applications, since smaller number of binding sites required (compared to depletion strategy) |