Fig. 3.

Cholesterol esterification by LCAT. rHDL made with WT apoA-I (*), apoA-I[R123A] (open circle), apoA-I[R123E] (open triangle), or apoA-I[R131A] (closed circle) and containing traces of [³H]cholesterol were used as a substrate in the CE formation assays. Increasing concentrations of rHDL were incubated with purified LCAT to get initial rate constants for CE formation, as described in the Materials and Methods. The cholesterol esterification rate is expressed in nanomoles of CE formed per hour of incubation per milliliter of LCAT and plotted against the substrate (rHDL cholesterol) concentrations. All points represent an average of two to three individual experiments of duplicate determinations for each cholesterol concentration.