FIGURE 3.

The hydrophobic loop core and its basic residue contribute to disulfide bond formation. L27 peptides and their mutants were dissolved in PBS or in a lipid suspension of 100 μm large LUVs to give a concentration of 13.3 μm, and oxidation was monitored for several hours. A, the percentage of oxidation as determined by the difference in DTNB reaction with free thiol groups before and after the oxidation. Black columns represent oxidation in PBS, whereas white columns represent oxidation in the presence of LUVs. Results are the mean ± S.D. (n = 3) of the percentage of the oxidized fraction out of the total amount of the peptide. B, oxidation kinetics were monitored by injecting samples to the RP-HPLC at different time points for the L27 WT loop peptides (■), L27 K601A mutant peptides (▵), and L27 L602A mutant peptides (□). For each time point, the percentage of peptide oxidation (mean ± S.D., n = 3) was determined by calculating the amount of the oxidized peptide divided by the total amount of the peptide injected.