FIG 6.

Fusion activity of E1 H331D/E, spring twist region cystine staple, and double-alanine mutants. The percentage of liposome content dilution was estimated as described in Materials and Methods. Average values from three experiments are plotted in the bar graph along with error bars. (A) Fusion activity comparison between the E1 wild type and H331D or H331E mutant. (B) Fusion activity comparison between the E1 wild type and spring-twisted region cystine staple mutant. One-way ANOVA was used to calculate statistical significance. **, ***, and **** represent P ≤ 0.01, P ≤ 0.001, and P ≤ 0.0001, respectively. ns, not significant.