FIG. 5.

pH dependence of hemolysis for wild-type and 4c-resistant mutants. A hemolysis assay was performed in which the pH of the acidic buffer was varied between 4.6 and 6.0. The y axis shows the degree of hemolysis, expressed as the optical density at 450 nm (OD₅₄₀) minus the blank value obtained from a mock-infected condition. 4c^r-A, 4c^r-B, and 4c^r-C, clones selected under 4c pressure; control, pooled data from three clones selected in the absence of compound. The values in parentheses are the pHs at which 50% hemolysis occurred relative to the value at pH 4.9.