As with all these things, YMMV. In our experience, chaperone co-expression can help not at all, can produce more folded protein or can produce more soluble protein, with co-purifying chaperone. With GroEL/S at least, chaperone release is easy (add ATP) and sometimes results in the liberation of folded protein, sometimes not.
One case where for us chaperones made an enabling difference: Acta Cryst. (2005). F61, 403–406 Like most things, worth trying! cheers Shaun
