Drops: 3. Precipitated protein.

3. Precipitated protein.

In the initial screen:

If the protein precipitated within 1 day repeat the condition with a lower precipitant concentration.

If the heavy precipitate is formed after a few days, the condition does not favor crystallization.
Evaluate unfavorable condition (pH, precipitant or additive)

---

This is not a good starting point. Protein possibly denatured, judged upon the dark/brown appearence of the precipitate.
Tip: Dilute the drop with water, if the protein does not dissolve, the protein is probably denatured.

---

In older drops a skin of denatured protein can appear on the surface of the drop.If the surface has a film that is not wrinkled it could be phase separation.