For instance, the kcat value of the best Kemp eliminase reported to date 36 (~700 ± 60 s -1 ) was determined from the analysis of a Michaelis plot in which saturation was not achieved and only a moderate curvature was observed, as is apparent in Figure of ref. , and similar curvatures are seen in most Michaelis plots reported here. Still, in order to ensure that the catalytic rate enhancements reported here are not artefactual, we have performed an extensive amount of experimental work under different conditions, including at different pH and acetonitrile concentrations, to allow for increased ranges of substrate concentration. The catalytic enhancements reported here are consistent over this variety of conditions.