1. ENZYMES Introduction 􀁡enzymes are proteins 􀁡enzymes are catalysts
􀁠speed up a chemical reaction by lowering the activation energy required
􀁡thousands of enzymes in cells
􀁠catechol oxidase will be tested

2. Factors that Affect Enzyme Activity
Factors that Affect EnzymeActivity for catechol oxidase
􀁡specificity
􀁠ability to discriminate between similar structures
􀁡temperature􀁠optimally, 40 C
􀁡pH􀁠optimally, pH 7
􀁡cofactors􀁠Cu++ (metallic ions

3. Enzyme Structure and Function
􀁡Enzyme (catechol oxidase in potato
extract)􀁠active site􀁠allosteric site
􀁡substrate (catechol) binds to active

4. Enzyme Structure and Function, cont
substrate and enzyme
(lactose) (lactase) enzyme-substrate complex
Products (glucose)

5. Specificity Procedure 􀁠tube L (enzyme + Lactose))
􀁠tube M (enzyme + Maltose)
􀁡 place tubes in 40 0C
􀁡Which tube shows more product formed

6. Temperature Procedure 􀁡place enzyme in appropriate temp. for 5 min
before testing
􀁠tube at 5 0C tube at 25 0C􀁠tube at 40 0C tube at 60 0C􀁠tube at 80 0C and tube at 100 0C
􀁡􀁡Which tube shows most product formed

7. pH 􀁡Procedure 􀁡Place enzyme in appropriate buffer for 5 min
before testing, place 40 0C
􀁠tube at pH 2 tube, at pH 4,􀁠tube at pH 6 tube at pH 7,pH 8,􀁠tube at pH 10 tube at pH 12
􀁡􀁡Which tube shows most product formed?

8. Cofactors 􀁡place tubes in 40 0C
􀁠tube C (enzyme + water + milksubstrate)
􀁠tube E (enzyme + EDTA + milksubstrate)
􀁡􀁡Which tube shows product formed?
􀁡*PTU (phenylthiourea is poisonous), Dispose in labeled containers