1.5 Enzymes Flashcards
How do enzymes act as biological catalysts?
• Lowers activation energy
• To speed up rate of reaction
What is the induced-fit model?
• Substrate binds to active site of enzyme but not fully complementary
• Causing active site to change shape slightly so it’s complementary to the substrate
• Forming an enzyme-substrate complex
• Straining bonds in the substrate, lowering activation energy
How are enzymes specific?
• Specific tertiary structure determines shape of active site
• Active site is complementary to a specific substrate
• Only this substrate can bind to active site, inducing fit, forming an enzyme-substrate complex
How does enzyme concentration effect rate of reaction?
• As enzyme concentration increases, rate of reaction increases
• More enzymes so more available active sites
• So more enzyme-substrate complexes form
• Rate levels off as substrate concentration becomes limiting factor
How does substrate concentration effect rate of reaction?
• As substrate concentration increases, rate of reaction increases
• More enzyme-substrate complexes form
• Rate levels off as all active sites saturated
How does temperature effect rate of reaction?
• As temperature increases, rate of reaction increases
• More kinetic energy
• So more enzyme-substrate complexes form
• If temperature exceeds optimum, rate of reaction decreases as enzymes denature (tertiary structure / active site changes shape as hydrogen bonds break so active site is no longer complementary so less enzyme-substrate complexes form)
How does pH affect rate of reaction?
• As temperature increases/decreases above/below optimum, rate of reaction decreases as enzymes denature (tertiary structure / active site changes shape as hydrogen bonds break so active site is no longer complementary so less enzyme-substrate complexes form)
How does concentration of competitive inhibitor effect rate of reaction?
• As concentration of competitive inhibitor increases, rate of reaction decreases
• Similar shape to substrate so binds to and blocks active site so substrate can’t bind
• So fewer enzyme-substrate complexes form
• Increasing substrate concentration reduces effect of inhibitor
How does concentration of non-competitive inhibitor effect rate of reaction?
• As concentration of non-competitive inhibitor increases, rate of reaction decreases
• Binds to enzyme away from active site, altering the tertiary structure so active site no longer complementary to substrate so substrate can’t bind
• So fewer enzyme-substrate complexes form
• Increasing substrate concentration has no effect on rate
