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Chemistry

The Kinetic Isotope Effect in Enzyme-Catalyzed Reactions

Quick fact

Replacing a hydrogen atom with deuterium can slow an enzyme-catalyzed reaction by up to 6-10 times, directly revealing that breaking the C-H bond is the rate-limiting step.

Why this is interesting

If enzymes are such perfect catalysts, why does swapping a single atom for a heavier twin slow them down—and why is that slowdown a goldmine for biochemists?