Biochemistry Enzyme Action Overview

Questions and Answers

What effect does increasing substrate concentration have on enzyme action?

No effect on enzyme action

Alters enzyme structure

Increases enzyme action (correct)

Decreases enzyme action

At what temperature does the optimum activity for most enzymes in the human body occur?

37°C (correct)

45°C

55°C

25°C

What is the immediate effect of low temperatures on enzyme activity?

Enzymes become inactive

Enzymes are enhanced

Enzyme action slows down (correct)

Enzymes are destroyed

Which factor significantly affects enzyme activity by causing conformational changes?

Substrate concentration Signup and view all the answers

What can occur when the pH level is outside of an enzyme's specific optimum range?

Decreased enzyme stability Signup and view all the answers

What is a common example of an enzyme inhibitor found in medicine?

Streptomycin Signup and view all the answers

Which metal ion is recognized as an accelerator of enzyme activity?

Iron (Fe) Signup and view all the answers

What is one potential environmental hazard to enzymes derived from cigarette smoke?

Cadmium (Cd) Signup and view all the answers

Which serum enzyme level is elevated in acute pancreatitis?

Amylase Signup and view all the answers

The presence of which substances commonly blocks enzyme catalysis?

Inhibitors Signup and view all the answers

What occurs after the substrate binds to the enzyme's active site?

An enzyme-substrate complex is formed. Signup and view all the answers

Which theory describes the enzyme and substrate fitting together like a key and lock?

Fischer's Lock and Key Theory Signup and view all the answers

What happens to the enzyme after the products are released?

The enzyme is recovered unchanged. Signup and view all the answers

Which of the following best describes activation energy?

Energy required to initiate a chemical transformation. Signup and view all the answers

In Koshland's Induced Fit Theory, what modifies the substrate or enzyme during binding?

Conformational changes. Signup and view all the answers

What is formed during the first step of the enzymatic action?

Enzyme-substrate complex. Signup and view all the answers

What is a key feature of Fischer's Lock and Key Theory?

Only compatible substrates can bind. Signup and view all the answers

What occurs as an outcome of the enzyme-substrate complex formation?

Catalytic reactions take place. Signup and view all the answers

How does temperature typically affect enzyme activity?

Can either increase or decrease activity depending on the enzyme. Signup and view all the answers

What role do enzymes play in biochemical reactions?

Decrease the energy required for reactions. Signup and view all the answers

Study Notes

Mode of Enzyme Action

Enzyme activity begins when the substrate contacts the active site of the enzyme.
An enzyme-substrate complex forms as a temporary intermediate.
The substrate is converted into products within the complex.
Products are released, and the enzyme remains unchanged, ready for another reaction.
Activation energy is the minimum energy needed for molecules to undergo transformation.

Theories Explaining Enzyme Action

Fischer's Lock and Key Theory: Enzyme and substrate fit together precisely like a key in a lock.
- The active site's structure is complementary to that of the substrate.
- The general reaction involves the formation and breakdown of the enzyme-substrate complex.
Koshland's Induced Fit Theory: Suggests that binding alters the shape of the enzyme or substrate.
- Initial binding of the substrate induces conformational changes for optimal fit and catalysis.

Factors Influencing Enzyme Action

Concentration of Substrate: Increasing substrate concentration enhances enzyme activity.
Concentration of Enzyme: Higher enzyme concentration leads to increased reaction rates.
Temperature:
- Optimum temperature for human enzymes is around 37°C.
- A 10°C increase can double or triple reaction rates.
- Excessive heat can inactivate enzymes, whereas low temperatures slow reactions without destroying enzymes.
pH Level: Each enzyme has a specific pH for maximum activity, with significant decreases in activity outside this range.
- Example: Pepsin (pH 1.5 to 2.2), Lactase (pH 5.7), Trypsin (pH 7.8).
Presence of Accelerators: Certain metallic ions (e.g., Mg, Mn, Co) can activate enzyme activity.
Presence of Inhibitors: Substances like antibiotics or antienzymes can inhibit enzyme activity through reversible or irreversible binding.
Environmental Hazards:
- Heavy metals such as Mercury (Hg), Cadmium (Cd), and Lead (Pb) from sources like cigarettes and gasoline can negatively affect enzyme function.

Clinical Enzymology

Enzymes serve as analytical tools for measuring substances in biological fluids, e.g., urease and alcohol dehydrogenase.
Enzymes are used as indicators for disease pathology.
- Elevated levels of certain enzymes, like amylase, lipase, and creatinine phosphokinase (CPK), can indicate various medical conditions (e.g., pancreatitis).

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Description

Explore the mechanisms behind enzyme action with this quiz. Learn about the formation of enzyme-substrate complexes, the theories explaining enzyme action, and factors influencing enzyme activity. Test your understanding of key concepts like Fischer's Lock and Key Theory and Koshland's Induced Fit Theory.