Chapter 19: Enzymes and Vitamins

Enzyme Definition: A protein that functions as a catalyst for a biological reaction.
Enzyme Function in Biochemical Reactions:
- An enzyme does not alter the energy or equilibrium of a chemical reaction.
- It may catalyze both energetically favorable and unfavorable reactions. However, an unfavorable reaction requires energy, typically in the form of ATP.
- The primary role of an enzyme is to decrease the time for a reaction to reach equilibrium by lowering the activation energy.
- These reactions integrate thermodynamics (energy), kinetics (rate of reaction progress), and potentially information about the reaction mechanism.
Characteristics of Enzymes:
- Most enzymes are water-soluble proteins found in the cell cytoplasm or the lumen of the gastrointestinal tract.
- Some enzymes are not water-soluble and are associated with various membranes of cellular organelles.
- Active Site: A