End products are the substances present at the conclusion of a reaction or pathway. Enzyme Structure and Function A. Enzymes mediate reversible reactions that tend to run toward chemical equilibrium. B. Four Features of Enzymes 1. Enzymes can be reused. Enzyme actions are reversible.
Enzymes are selective and act upon specific substrates.
C. Enzyme-Substrate Interactions 1. Activation energy is the amount of energy needed to bring colliding molecules to the transition state. Enzymes increase the rate of a reaction by lowering the activation energy through extensive bonding of substrate at the active site. The active site is a crevice where the substrate binds to the enzyme during a reaction according to the induced-fit model. Factors Influencing Enzyme Activity A. Enzymes and the Environment 1.