Enzymes

Enzymes

• They have the ability to change the rate of the reaction (i.e. they make slow reactions faster).
• Enzymes are types of catalysts. This means they help a reaction, but they are not used up in the process of the reaction.
• The name of an enzyme ends with "ase." Example: Synthase, lactase.
• Enzymes lower the activation energy of reactions (EA) which means they lower the energy required for the reaction to occur.
• They DO NOT change a reactions free energy (ΔG).
• They work by stabilizing the transition state:

Enzymes Specificity

• Induced fit – active site changes upon substrate binding for better fit/catalysis.
• The active site holds the molecules in a position that promotes a reaction to occur.

Enzyme Activity

Enzyme Activity And Its Effect On the Rate of a Reaction

• Substrate concentration ––> the more substrate (substance reacting), the faster the reaction rate is going to be. Analogy: a cashier is only busy when there are customers around.
• Temperature and pH ––> Enzymes often only work at a specific temperature and pH. If they don't have the correct environment, they will denature (loose its shape). Example: pepsin (stomach enzyme) works best at pH 2.0.
• Enzyme activity can be helped by cofactors or coenzymes (small helper molecules). Example: cofactors include vitamin B6, zinc, and magnesium (these are NOT proteins).