1 Enzymes

2 What Are Enzymes? ProteinsMost enzymes are Proteins CatalystAct as Catalyst to accelerate a reaction Not permanentlyNot permanently changed in the process

3Enzymes catalyzeAre specific for what they will catalyze ReusableAre Reusable aseEnd in –ase-Sucrase-Lactase-Maltase

4 How do enzymes Work? weakening bonds which lowers activation energy Enzymes work by weakening bonds which lowers activation energy

5Enzymes Free Energy Progress of the reaction Reactants Products Free energy of activation Without Enzyme With Enzyme

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7 Enzyme-Substrate Complex substance enzyme substrate The substance (reactant) an enzyme acts on is the substrate Enzyme Substrate Joins

8 Active Site restricted region enzyme bindssubstrateA restricted region of an enzyme molecule which binds to the substrate. Enzyme Substrate Active Site

The Lock and Key Hypothesis Fit between the substrate and the active site of the enzyme is exact This explains enzyme specificity 9

10 What Affects Enzyme Activity? 1.Substrate concentration: higher concentration increases velocity of reaction 2.pH: there is an optimum level for each enzyme; extreme pH levels causes denaturation of enzymes (change in structure)

3. Temperature: for most enzymes, optimum temperature is around 30 o C (86 o F); most enzymes denature at 70 o C (158 o F) 11

4. Inhibitors: chemicals that reduce the rate of enzymatic reactions; they block the enzyme but do not destroy it; many drugs and poisons are inhibitors of enzymes in the nervous system 12