Excessive Substrate Concentration or Incubation Time

Symptom

Rapid color development with all wells turning dark quickly. Signal may exceed linear range of reader (OD >2.0). Background wells show significant color development.

1. 1 Substrate concentration too high for enzyme activity present
2. 2 Substrate incubation time too long allowing excessive product formation
3. 3 Substrate incubation temperature too high accelerating reaction
4. 4 Delay in reading plate after stop solution addition causing signal drift

1. 1 Dilute substrate working solution to reduce reaction rate
2. 2 Decrease substrate incubation time (typically 15-30 minutes)
3. 3 Perform kinetic reading at 600-620nm, add stop solution when OD reaches ~1.0
4. 4 Read plate immediately within 5-10 minutes after adding stop solution
5. 5 Incubate substrate at room temperature, avoid elevated temperatures

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