FIGURE 4.

KAR activity of MabA_WT and mutant derivatives. A, reaction scheme for the reduction of acetoacetyl-CoA by MabA. B, MabA_WT, as well as MabA_T191A and MabA_T191D mutants, were purified from recombinant E. coli, dialyzed, and assayed for KAR activity in the presence of acetoacetyl-CoA and NADPH in 100 mm HEPES, pH 7.0, at 25 °C. Conversion of NADPH to NADP was monitored spectrophotometrically at 340 nm. The activity of MabA_WT was arbitrarily fixed at 100%. The values are means of triplicates and are representative of two sets of experiments done with independent protein preparations.