Microfuge Test

The Microfuge Test is a simple test that can be performed to make sure that your sample is not aggregating. This test should be performed on all samples prior to shipping. The following steps are involved:

  1. prepare 1 ml of a high concentration (4-5 mg/ml) sample of your protein.
  2. measure the absorbance at 280 nm (or 230 nm, if there is no absorbance at 280). Dilute as necessary. Never trust a measurement above 0.9 OD (nonlinearity of optics!).
  3. spin sample for 20 minutes in microfuge.
  4. Carefully aspirate a small amount of the supernatant, without disturbing the solution.
  5. Measure the OD. If the OD is reduced, the sample is aggregating.
  6. If the sample is OK, repeat the microfuge test after storing it for 2-3 days at the same temperature at which the AUC experiment will be performed.

If the OD of the supernatant does not change over time, the sample is suitable for AUC analysis.