Enzyme Kinetics

Enzyme Kinetics

1. Michaelis Constant (Km)

   • [Substrate] when rxn rate = 1/2 Vmax
     • Indicates [Substrate] needed to speed up rxn
       • High [substrate] means low affinity for substrate
         • Km inversely proportional to enzyme-substrate affinity

2. Vmax

   • Maximum rxn rate

3. Saturation Kinetics

   • [Substrate] increase, rate of rxn increases until Vmax is achieved

4. Cofactor

   • Non-protein component required by some enzymes to reach optimal activity
     • Can be coenzymes or metal ions
       • Coenzymes
         • Organic molecules
           • Water-soluble vitamins
           • Cosubstrates
             • Reversibly bind to an enzyme, transfer a chemical group to another substrate
               • Reverts to original form via other enzymatic rxn
                 • Example: ATP
           • Prosthetic groups
             • Binds covalently to enzyme during rxn
               • Emerges from rxn unchanged
                 • Example: Heme
                   • Heme binds to Catalase in peroxisomes to degrade H2O2
       • Metal Ions