Reversed-phase liquid chromatography as a useful probe of hydrophobic interactions involved in protein folding and protein stability.

We have evaluated the potential of reversed-phase liquid chromatography (RPLC) as a probe of hydrophobic interactions involved in protein folding and stability. Our approach was to apply RPLC to a de novo designed model protein system, namely a two-stranded alpha-helical coiled coil. It was shown that the reversed-phase retention behaviour of various synthetic analogues of monomeric alpha-helices and dimeric coiled-coil structures correlated well with their stability in solution, as monitored by circular dichroism during guanidine hydrochloride and temperature denaturation studies. In addition, an explanation is offered as to why amphipathic coiled coils, an important structural motif in many biological systems, are more stable at low pH compared to physiological pH values. The results of this study suggest that not only may RPLC prove to be a useful and rapid complementary technique for understanding protein interactions, but also the de novo designed coiled-coil model described here is an excellent model system for such studies.