E. Factors that slow down Enzyme Activity

1. pH-there is an optimum pH for every enzyme; peak of the bell curve.  Moving away from that pH will slow down the activity gradually until it reaches 0.
2. Temperature- also has an optimum number for each enzyme. As temp. decreases activity decreases gradually; as temp. increases a point will be reached where the enzyme denatures and all activity will stop.

 F. Regulation of Enzyme Activity

1. Allosteric Enzymes- have 2 binding sites; 1, the active site, for the substrate & 2, the allosteric site, for regulatory chemical. 2 actions:
• Activation
• Enzyme will be inactive as long as its allosteric site is uninhabited
• When an activator molecule bonds to the allosteric site this changes the shape of the active site, making it "fit" the substrate. Result: Catalysis
• Repression
• an enzyme will remain active as long as its allosteric site is uninhabited
• Repressor molecule bonds to the allosteric site changing the active site and making it "not fit" the substrate. Result: Stops Catalysis

G. Enzyme Inhibition- 2 Ways

1. Allosteric Repression- Non-competitive inhibition- repressor molecule is not competing for the active site.
2. Competitive Inhibition-  another molecule similar in structure to the substrate bonds to the active site, not allowing the real substrate to come in and bond.