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Questions and Answers
What suffix do enzymes typically have?
What suffix do enzymes typically have?
- ase (correct)
- ite
- ine
- in
What role do enzymes play in chemical reactions?
What role do enzymes play in chemical reactions?
- They increase the activation energy required.
- They completely consume substrates during the reaction.
- They act as substrates for other reactions.
- They speed up reactions by lowering activation energy. (correct)
Which of the following is an example of an enzyme?
Which of the following is an example of an enzyme?
- Lactic acid
- LDH (correct)
- NADH
- Pyruvic acid
What is one of the primary functions of enzymes in the body?
What is one of the primary functions of enzymes in the body?
In the context of enzyme action, what does the term 'transition state' refer to?
In the context of enzyme action, what does the term 'transition state' refer to?
What type of inhibitors does Orlistat represent?
What type of inhibitors does Orlistat represent?
Which enzyme does Orlistat inhibit?
Which enzyme does Orlistat inhibit?
What is the primary effect of Orlistat on fat absorption?
What is the primary effect of Orlistat on fat absorption?
Which of the following is NOT an example of an irreversible inhibitor?
Which of the following is NOT an example of an irreversible inhibitor?
What is a consequence of Orlistat inhibiting pancreatic lipase?
What is a consequence of Orlistat inhibiting pancreatic lipase?
What characterizes reversible inhibitors?
What characterizes reversible inhibitors?
Which of the following is NOT a characteristic of irreversible inhibitors?
Which of the following is NOT a characteristic of irreversible inhibitors?
What is a common feature of reversible inhibitors?
What is a common feature of reversible inhibitors?
Which of the following statements is true regarding enzyme inhibitors?
Which of the following statements is true regarding enzyme inhibitors?
What can increase the likelihood of inhibition by reversible inhibitors?
What can increase the likelihood of inhibition by reversible inhibitors?
What is the role of an allosteric inhibitor in enzyme function?
What is the role of an allosteric inhibitor in enzyme function?
How does increasing substrate concentration affect allosteric inhibition?
How does increasing substrate concentration affect allosteric inhibition?
What type of enzyme inhibitor is designed to mimic the transition state of a reaction?
What type of enzyme inhibitor is designed to mimic the transition state of a reaction?
What happens to the enzyme's active site when an allosteric inhibitor binds?
What happens to the enzyme's active site when an allosteric inhibitor binds?
What characteristic do transition-state inhibitors share with substrates or products?
What characteristic do transition-state inhibitors share with substrates or products?
What bonds are formed between an allosteric inhibitor and the enzyme?
What bonds are formed between an allosteric inhibitor and the enzyme?
Which type of inhibitors generally bind most strongly to the active site?
Which type of inhibitors generally bind most strongly to the active site?
What is a key difference between an allosteric inhibitor and a substrate?
What is a key difference between an allosteric inhibitor and a substrate?
Which type of bonding force is NOT involved in substrate binding?
Which type of bonding force is NOT involved in substrate binding?
What role does ionised histidine play in acid/base catalysis?
What role does ionised histidine play in acid/base catalysis?
What effect does an allosteric inhibitor have on an enzyme?
What effect does an allosteric inhibitor have on an enzyme?
Which statement about enzyme regulation through feedback control is true?
Which statement about enzyme regulation through feedback control is true?
What do binding interactions in enzyme catalysis need to strike a balance between?
What do binding interactions in enzyme catalysis need to strike a balance between?
What is the purpose of the allosteric site on an enzyme?
What is the purpose of the allosteric site on an enzyme?
Which amino acid can act as a nucleophile in enzymatic reactions?
Which amino acid can act as a nucleophile in enzymatic reactions?
What occurs to the active site when an allosteric inhibitor binds?
What occurs to the active site when an allosteric inhibitor binds?
Why do stronger binding interactions in enzyme inhibitors block the active site?
Why do stronger binding interactions in enzyme inhibitors block the active site?
In what way does an allosteric activator differ from an allosteric inhibitor?
In what way does an allosteric activator differ from an allosteric inhibitor?
What does the 'induced fit' model suggest about enzyme and substrate interactions?
What does the 'induced fit' model suggest about enzyme and substrate interactions?
How does the transition state relate to substrate binding?
How does the transition state relate to substrate binding?
What type of catalysis does histidine perform when it acts as a proton sink?
What type of catalysis does histidine perform when it acts as a proton sink?
What is a characteristic of enzymatic reactions in biosynthetic pathways?
What is a characteristic of enzymatic reactions in biosynthetic pathways?
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Study Notes
Structure and Function of Enzymes
- Enzymes typically end with the suffix "ase".
- Globular proteins serve as catalysts, increasing reaction speed to reach equilibrium.
- They lower the activation energy needed for reactions.
Enzyme Interaction with Substrates
- Substrates bind to the enzyme's active site through various interactions: hydrogen bonds, van der Waals forces, and ionic bonds.
- Effective substrate binding relies on a balance of strong and weak interactions to stabilize the transition state.
Catalysis Mechanisms
- Acid/base catalysis occurs with residues like histidine, which alternates between basic and acidic states.
- Nucleophilic residues, like L-Serine and L-Cysteine, contribute to catalytic activity through their side chains.
Regulation of Enzymes
- Allosteric inhibitors bind to sites distinct from the active site, altering the enzyme's shape and preventing substrate recognition.
- Inhibition is not overcome by increased substrate concentration and involves structural differences between the inhibitor and substrate.
Biosynthetic Pathways and Feedback Control
- Allosteric enzymes often regulate the beginning of biosynthetic pathways.
- The final product of a pathway can inhibit the pathway's initial enzyme, demonstrating feedback control.
Overall Process of Enzyme Catalysis
- The binding of substrates requires sufficient duration for the reaction, with stable interactions during transition states.
- Strong binding interactions can lead to enzyme inhibitors that block the active site from substrates.
Types of Enzyme Inhibitors
-
Reversible inhibitors bind to the active site through weak intermolecular bonds and can be displaced by increased substrate concentration.
- Examples include diuretics, ACE inhibitors, and statins.
-
Irreversible inhibitors form covalent bonds with enzymes, inhibiting substrate access regardless of concentration.
- Examples include nerve gases and penicillins.
Orlistat as a Case Study
- Orlistat inhibits pancreatic lipase, blocking fat digestion in the intestine.
- This results in reduced absorption of fatty acids and glycerol, decreasing fat synthesis in the body.
Allosteric Inhibitors
- Function by binding reversibly to allosteric sites, causing shape alterations in enzymes that hide the active site.
- Inhibition remains even with high substrate concentrations, and the inhibitor differs from substrate structure.
Transition State Inhibitors
- Designed to mimic the transition state in enzyme reactions.
- Bind tightly to active sites and can be thermodynamically stable, offering a potential method for drug design, such as Saquinavir used in HIV treatment.
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