As a result of these errors the values of the inactivation rates (Kapp) at different chalepensin concentrations, kinact (maximal inactivation rate constant of chalepensin) and KI (chalepensin concentration required for half-maximal inactivation) were incorrect.
Further errors appeared on pages 1250, 1254 and 1256 and are corrected by the following:
In the Key Results section of the abstract on page 1250 the sentence beginning ‘This time-dependent inactivation . . .’ should read ‘This time-dependent inactivation (kinact 0.298 min−1; KI 4.8 µM) caused the loss of spectrally detectable P450 content and was diminished by known inhibitors of CYP2A6, pilocarpine or tranylcypromine, and by glutathione conjugation.’
In the Data and kinetic analyses section of the Methods on page 1254 ‘Lineweaver-Burke plots’ should be ‘Lineweaver-Burk plots’. In the same section the sentence beginning ‘The kinact . . .’ should read ‘The kinact (maximal inactivation rate constant of chalepensin) and KI (chalepensin concentration required for half-maximal inactivation) values were estimated from nonlinear regression from the equation Kapp= (kinactI)/(I+KI) with the initial values calculated from the double reciprocal plot of inactivation rate versus chalepensin concentration (Silverman, 1995).’
In the The metabolism-dependence and kinetic analysis of the CYP2A6 inhibition by chalepensin section of the Results on page 1254 the paragraph beginning ‘Pre-incubation with NADPH and chalepensin . . .’ should read ‘Pre-incubation with NADPH and chalepensin induced a time-dependent inactivation of coumarin 7-hydroxylation activity with kinact of 0.298 ± 0.044 min−1 and apparent KI of 4.8 ± 1.8 µM (Figures 1D,E). Linear regression analysis of the double reciprocal plots for inactivation rate and chalepensin concentration generated the kinact and apparent KI values for CYP2A6 of 0.233 min−1 and 2.6 µM respectively (Figure 1F).’
In the Discussion and conclusions on page 1256 the sentence beginning ‘In the presence of NADPH . . .’ should read ‘In the presence of NADPH, the efficiency of enzyme inactivation by chalepensin, calculated as the ratio of kinact to KI was 62.1 min−1 mM−1.’
The errors in the figure and text do not change the conclusion of the study.