Heating of proteins as a means of improving crystallization: a successful case study on a highly amyloidogenic triple mutant of human transthyretin

The use of high temperatures in the purification procedures of heat-stable proteins is a well established technique. Recently, rapid pre-heat treatment of protein samples prior to crystallization trials was described as a final polishing step to improve the diffraction properties of crystals [Pusey et al. (2005), Prog. Biophys. Mol. Biol. 88, 359-386]. The present study demonstrates that extended high-temperature incubation (328 K for 48 h) of the highly amyloidogenic transthyretin mutant TTR G53S/E54D/L55S successfully removes heterogeneities and allows the reproducible growth of well diffracting crystals. Heat treatment might be applied as an optimization method to other cases in which the protein/biomolecule fails to form diffracting crystals.