Correction to "Evaluating the Catalytic Contribution from the Oxyanion Hole in Ketosteroid Isomerase".

W report that the kinetic constants for several mutants of ketosteroid isomerase (KSI) from our 2011 publication are incorrect. Jason Schwans and Daniel Herschlag, the paper’s first and corresponding authors, take full responsibility for and deeply regret these errors. Based on extensive control experiments, the errors likely arose from low levels (∼0.1−1%) of contaminating wild-type enzyme introduced during fast protein liquid chromatography (FPLC) purification; this contamination can be avoided by stringent washing of the FPLC injection loop and other plumbing with base (Supplemental text). The main conclusions of the Communication are not affected by these errors. For clarity, we list below the central conclusions from our work and how they are or are not altered by these errors. Also, we remeasured kinetic constants from two papers we published around the same time and found all of those results to be fully reproducible (Supplemental Table 1). All remeasured values are presented as Supporting Information and directly compared to those from the prior work (Supplemental Tables 2−5). Additional measurements were made with a faster-reacting substrate and with several additional mutant enzymes to extend these measurements and comparisons in light of the new findings (Supplemental Tables 6 and 7). Inhibition constants were determined for several mutants to provide evidence that the new kinetic constants correspond to the mutant activities and not wild-type contamination (Supplemental Tables 8 and 9). Prior and Updated Conclusions: 1. The oxyanion hole catalytic contribution is overestimated by so-called conservative mutations. This conclusion holds.