How pure should my protein be with the NexTal CubicPhase kits?
FAQ ID -2414

Protein crystallization requires highly pure proteins, typically >95% (as evaluated by SDS-PAGE or gel filtration chromatography). However, crystallization in lipidic cubic phase can accommodate lower purity, and has been reported to work with samples as little as 50% pure.

Ref: C. A. Kors, E. Wallace, D. R. Davies, L. Li, P. D. Laible and P. Nollert Effects of impurities on membrane-protein crystallization in different systems Acta Cryst. (2009). D65, 1062-1073