Displacement statistics of unhindered single molecules show no enhanced diffusion in enzymatic reactions

ABSTRACT Recent studies have sparked heated debate over whether catalytical reactions would enhance the diffusion coefficients D of enzymes. Through high statistics of the transient (600 μs) displacements of unhindered single molecules freely diffusing in common buffers, we here quantify D for four highly contested enzymes under catalytic turnovers. We thus formulate how precisions of better than ±1% may be achieved for D at the 95% confidence level, and show no changes in diffusivity for catalase, urease, aldolase, and alkaline phosphatase under the application of wide concentration ranges of substrates. Our single-molecule approach thus overcomes potential limitations and artifacts underscored by recent studies to show no enhanced diffusion in enzymatic reactions. Table of Contents artwork