Studies on the Conformation of Apocytochrome c in Different Folding States Inserted into the Membranes.

Correlation between the folding states of the chicken heart apocytochrome c and its membrane insertion ability was studied by the monolayer experiment. The penetration ability of apocytochrome c decreased with its folding. Intrinsic fluorescence emissions of apocytochrome c interacted with soybean phospholipids liposomes suggested that the conformations of apocytochrome c with different folding states in aqueous solution were also different in the membranes. The conformational differences were further characterized by CD spectra of apocytochrome c interacted with DMPC and DMPG liposomes. The results showed that apocytochrome c, which were randomly coiled in aqueous solution, adopted alpha-helical conformations after interaction with DMPG liposome. The apocytochrome c with a folded state in aqueous solution also adopted alpha-helical conformations, but the alpha-helical contents were less than the former. When DMPC liposomes were used, no distinct conformational change was observed.

The Self-association of Melittin at Low Concentration in Aqueous Solution.

The intrinsic fluorescence emission, polarization and Trp-19 quenching of melittin in the aqueous solution showed that even with concentration as low as 2 &mgr;M, the self-association of melittin still occurred. The transition preferred to occur under acidic condition and the stability of the associated melittin was dependent on the pH value of the solution.