Enzyme Targets in Medicine

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Questions and Answers

What suffix do enzymes typically have?

ase (correct)

ite

ine

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?

Lactic acid

LDH (correct)

NADH

Pyruvic acid

What is one of the primary functions of enzymes in the body?

To facilitate and accelerate biochemical reactions. Signup and view all the answers

In the context of enzyme action, what does the term 'transition state' refer to?

The point at which substrates convert to products. Signup and view all the answers

What type of inhibitors does Orlistat represent?

Irreversible inhibitors Signup and view all the answers

Which enzyme does Orlistat inhibit?

Pancreatic lipase Signup and view all the answers

What is the primary effect of Orlistat on fat absorption?

Reduces fat absorption Signup and view all the answers

Which of the following is NOT an example of an irreversible inhibitor?

Ibuprofen Signup and view all the answers

What is a consequence of Orlistat inhibiting pancreatic lipase?

Reduced biosynthesis of fat Signup and view all the answers

What characterizes reversible inhibitors?

They bind to the active site through intermolecular bonds. Signup and view all the answers

Which of the following is NOT a characteristic of irreversible inhibitors?

Inhibition can be overcome by increasing substrate concentration. Signup and view all the answers

What is a common feature of reversible inhibitors?

Inhibition is dependent on inhibitor concentration. Signup and view all the answers

Which of the following statements is true regarding enzyme inhibitors?

Reversible inhibitors do not undergo any reaction. Signup and view all the answers

What can increase the likelihood of inhibition by reversible inhibitors?

Increasing the strength of inhibitor binding. Signup and view all the answers

What is the role of an allosteric inhibitor in enzyme function?

It binds to the allosteric site and alters enzyme shape. Signup and view all the answers

How does increasing substrate concentration affect allosteric inhibition?

It has no effect on the inhibition. Signup and view all the answers

What type of enzyme inhibitor is designed to mimic the transition state of a reaction?

Transition state inhibitors Signup and view all the answers

What happens to the enzyme's active site when an allosteric inhibitor binds?

The active site is distorted and unrecognizable. Signup and view all the answers

What characteristic do transition-state inhibitors share with substrates or products?

They are thermodynamically stable. Signup and view all the answers

What bonds are formed between an allosteric inhibitor and the enzyme?

Intermolecular bonds Signup and view all the answers

Which type of inhibitors generally bind most strongly to the active site?

Transition state inhibitors Signup and view all the answers

What is a key difference between an allosteric inhibitor and a substrate?

Allosteric inhibitors are not similar in structure to substrates. Signup and view all the answers

Which type of bonding force is NOT involved in substrate binding?

Covalent bonds Signup and view all the answers

What role does ionised histidine play in acid/base catalysis?

It acts as a proton source. Signup and view all the answers

What effect does an allosteric inhibitor have on an enzyme?

It induces a conformational change that alters the active site. Signup and view all the answers

Which statement about enzyme regulation through feedback control is true?

The final product of a pathway can inhibit the first enzyme. Signup and view all the answers

What do binding interactions in enzyme catalysis need to strike a balance between?

Sufficient strength and sufficient weakness. Signup and view all the answers

What is the purpose of the allosteric site on an enzyme?

To regulate enzyme activity. Signup and view all the answers

Which amino acid can act as a nucleophile in enzymatic reactions?

L-Serine Signup and view all the answers

What occurs to the active site when an allosteric inhibitor binds?

It undergoes shape changes making it unrecognizable. Signup and view all the answers

Why do stronger binding interactions in enzyme inhibitors block the active site?

They prevent correct substrate alignment. Signup and view all the answers

In what way does an allosteric activator differ from an allosteric inhibitor?

Activators enhance enzyme activity. Signup and view all the answers

What does the 'induced fit' model suggest about enzyme and substrate interactions?

The enzyme and substrate undergo conformational changes. Signup and view all the answers

How does the transition state relate to substrate binding?

It stabilizes substrate interaction for the reaction to occur. Signup and view all the answers

What type of catalysis does histidine perform when it acts as a proton sink?

Base catalysis Signup and view all the answers

What is a characteristic of enzymatic reactions in biosynthetic pathways?

The end product often regulates an early enzyme. Signup and view all the answers

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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Description

This quiz explores the structure and function of enzymes, focusing on their role as catalysts in biological reactions and their significance in developing medications. Participants will learn about enzyme properties, naming conventions, and mechanisms that lower activation energy. Test your knowledge on how these biological catalysts are utilized in modern medicine.