Abstract

The mechanisms by which osmolytes increase the biocatalytic efficiency of enzymes are still not well understood. In a joint computational and experimental study, we identified different effects, depending on the type of osmolyte, on the catalytic activity of formate dehydrogenase from Candida boidinii (CbFDH), an industrially relevant enzyme. These effects are related to enzyme inter-domain fluctuations, solvation, and active site dynamics as well as substrate residence times. The combination of these factors could explain the experimental behavior of the kcat of CbFDH in different osmolyte solutions, compared to buffer. Our computational studies also allowed us to propose six routes, located at the interface between both domains of CbFDH, for water trafficking and formate exit between the active site of CbFDH and the solvent. The results suggest that solvent-induced changes might affect the route's dynamics and, potentially, the catalytic activity of CbFDH. Our comprehensive analysis of protein solvation, structure, and dynamics thus provides a molecular understanding of the role of these osmolytes on enzymatic activity.