High level expression of non-native genes often results in the target protein becoming insoluble. Potential solutions are:

• Induce at a lower temperature (as low as 15°C overnight)
• Reduce IPTG concentration to 40 μM
• Induce earlier in growth phase (OD₆₀₀ = 0.3–0.4) and harvest cells earlier.
• Create an expression construct where the target protein is fused to maltose binding protein (pMAL Protein Fusion and Purification System, NEB #E8200).