enzymes biomolecules that catalyze chemical reactions - increase reaction rates - specific...
TRANSCRIPT
EnzymesBiomolecules that catalyze chemical reactions
- Increase reaction rates
- Specific
Oxidoreductases – catalyze redox reactions
Transferases – transfer groups such as –CH3 or -NH2
Hydrolases – catalyze hydrolysis reactions
Lyases – catalyze the removal or addition of double bonds
Isomerases – catalyze isomerization reactions
Ligases – catalyze the joining of two molecules
Terms
Substrate - a compound that binds to the enzyme and is processed
Active Site - region (pocket or cleft) in the enzyme where the substrate binds
Activation - an increase in enzymatic activity (how well an enzyme works)
Enzyme Activity
- a measure of the rate of the reaction catalyzed by the enzyme
Inhibition - a decrease in enzyme activity
Inhibitor - a molecule that binds to the enzyme and inhibits activity
Mechanism of Enzyme ActionLock and Key
Induced Fit - substrate binding induces conformational changes
(structural changes) in the enzyme that promote catalysis
Lock and Key
E + S
Lock and Key
E + S ES
Lock and Key
E + S ES E + P
Induced Fit
E + S
Induced Fit
E + S
Induced Fit
E + S ES
Induced Fit
E + S ES E + P
Example: Hexokinase
Hexokinase specifically binds both glucose and ATPHexokinase speeds up the reaction
Glucose Binding
Glucose Binding
Hexokinase binds Glucose and ATP
Substrate binding is governed by intermolecular forces
Example of Induced Fit
Example of Induced Fit
Citrate Synthase
Krebs Cycle
Citrate Synthase
Factors that effect enzyme activity
Enzyme and Substrate Concentration
Temperature
pH
Inhibitors
E + S ES → E + P⇌
Competitive vs Noncompetitive Inhibition
Some Drugs are Enzyme Inhibitors
• Certain drugs bind to Enzymes and prevent binding of the normal substrates
• The enzyme is thus prevented from catalyzing a physiological reaction
HIV Drugs
N NH
O
NH
O
O
NH2
NH
O
NH3+
O
NH
O
O