The ability of apocytochrome C to pass lipid bilayer is relevant with its folding state.

The translocation ability of two different species of apocytochrome c(horse heart, Candida krusei) across the soybean phospholipid vesicles decreased in the order: C. krusei > horse heart. Theoretical calculations of the amphiphilicity of their N- and C-terminal alpha-helix formation and the release experiment using calcein-enclosed soybean phospholipid vesicles showed that there was no direct relevance between their import ratio and the amphiphilic helicity. On the other hand, taking the advantage of circular dichroism technique, a more loosely folded structure of C. krusei following the interaction with soybean phospholipid vesicles was observed which should be responsible for the difference in translocation rate.