VOLUME 285 (2010) PAGES 18085–18094
The kinetic parameters, particularly Km, for methionine sulfoxide reductase A reported in Table 2 are not correct because an excessive fraction of substrate was consumed in the assays. We have redetermined the parameters, taking care to limit substrate consumption to ≤13%. Enzyme activity was determined with l-MetO as substrate with concentrations varying between 0.10 and 5.0 mm. The concentration of MsrA was 53 nm. The results were fit to Michaelis-Menten kinetics with Prism (version 6, GraphPad Software). The parameters were determined on two separate days, and the results were averaged. The error does not affect the conclusions of the paper.
TABLE 2.
Kinetic parameters of myristoylated and non-myristoylated recombinant MsrA
Species | MsrA | Km for (S)-MetOa | Vmax | Kcat |
---|---|---|---|---|
mm | μmol/min/mg | s−1 | ||
Mouse | Non-myristoylated | 0.79 | 4.8 | 1.9 |
Mouse | Myristoylated | 0.96 | 5.0 | 2.0 |
Human | Non-myristoylated | 1.06 | 5.5 | 2.2 |
Human | Myristoylated | 0.90 | 5.0 | 2.0 |
a The Km was calculated for (S)-MetO as MsrA is specific for this epimer (30).