Enzymes use substrate-binding energy to promote ground-state association and to selectively stabilize the reaction transition state. Mutations in the amino-terminal domain of the monomeric homing endonuclease I-AniI, which cleaves with high sequence specificity in the centre of a 20-base-pair DNA target site, are now found to have different effects on the kinetic parameters of the enzyme than those in the carboxy-terminal domain, revealing an unexpected asymmetry in the use of enzyme–substrate binding energy for catalysis.
- Summer B. Thyme
- Jordan Jarjour
- David Baker
