Ub-AMC vs Ub-Rho110: A Practical Guide to Fluorogenic Substrate Selection
Key Differences Between the Two Substrates
While both Ub-AMC and Ub-Rho110 are ubiquitin C-terminal fluorogenic substrates, they differ fundamentally in fluorophore characteristics:
| Dimension | Ub-AMC | Ub-Rho110 |
|---|---|---|
| Fluorophore | AMC (coumarin) | Rhodamine 110 |
| Excitation/Emission | 345 nm / 440 nm | 498 nm / 520 nm |
| Quantum Yield | Moderate | High (~3–5× AMC) |
| Sensitivity | nM range | pM range |
| Autofluorescence | UV region, prone to interference | Visible region, minimal interference |
| Cost per assay | Low | Medium |
Selection Guide
Choose Ub-AMC when:
- Routine DUB activity detection at nM enzyme concentrations
- Enzyme kinetics (Km/kcat) determination
- Reaction condition optimization (buffer, pH, temperature)
- Teaching labs or budget-conscious projects
Choose Ub-Rho110 when:
- High-throughput screening requiring excellent Z' factor
- Low-concentration DUB detection (pM range)
- Measurements in complex biological matrices (serum, lysates)
- Long-duration kinetic monitoring requiring photostability
FAQ
Can Ub-AMC be used for HTS? Yes, but the Z' factor is typically lower than Ub-Rho110. For large-scale compound library screening, Ub-Rho110's superior S/N ratio translates to lower false positive/negative rates.
Can both substrates be mixed? Theoretically possible but not recommended — different Ex/Em require separate detection channels and may cause mutual interference.