Lecture 25

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What do the terms Km and V maxrepresent in enzyme kinetics?

Constants for enzyme stability

Parameters for reaction equilibrium

Michaelis constant and maximum reaction velocity (correct)

Rates of substrate binding and release

How can Km and V max be estimated using the Lineweaver-Burk plot?

By taking the reciprocals of the Michaelis-Menten equation (correct)

By observing enzyme stability at different temperatures

By measuring the final product concentration

By plotting enzyme concentration against substrate concentration

What type of curve does the Michaelis-Menten equation produce when plotted?

Linear

Rectangular hyperbola (correct)

Exponential

Parabolic

What is a major drawback of using the Lineweaver-Burk plot?

It can be influenced by errors at low v0 . Signup and view all the answers

How does increasing temperature typically affect enzyme activity?

It can increase activity up to a point, then cause denaturation. Signup and view all the answers

What is the effect of pH on enzyme activity?

It can denature enzymes at extreme pH levels. Signup and view all the answers

What type of inhibitor is penicillin, and how does it affect bacterial enzymes?

Irreversible inhibitor; it permanently binds to active sites. Signup and view all the answers

Which of the following is a mechanism of irreversible enzyme inhibition?

Covalent modification Signup and view all the answers

What effect does a competitive inhibitor have on Km?

It increases Km Signup and view all the answers

In noncompetitive inhibition, how does the presence of the inhibitor affect Vmax?

V max decreases Signup and view all the answers

What type of inhibitor mimics the substrate and competes for the active site?

Competitive inhibitor Signup and view all the answers

What is the role of acetylcholinesterase in neurotransmission?

It degrades acetylcholine to terminate signaling. Signup and view all the answers

Which nerve agent irreversibly inhibits acetylcholinesterase?

Sarin Signup and view all the answers

What is the effect of a noncompetitive inhibitor on the enzyme-substrate complex?

It does not affect substrate binding but decreases product formation. Signup and view all the answers

What happens to enzyme activity when the temperature exceeds the optimal range?

Enzyme denaturation may occur, reducing activity. Signup and view all the answers

What does the term "allosteric regulation" refer to?

Binding at a site other than the active site, altering enzyme activity Signup and view all the answers

What is the primary mechanism by which salicylic acid (aspirin) acts as a pain reliever?

It irreversibly inhibits cyclooxygenase. Signup and view all the answers

In the Lineweaver-Burk plot, what do the x-intercept and y-intercept represent?

-1/Km and 1/V max Signup and view all the answers

How does temperature affect the kinetic parameters Km and Kcat?

it can alter both Km and Kcat Signup and view all the answers

Which of the following factors does NOT influence enzyme kinetics?

Enzyme color Signup and view all the answers

What is the primary effect of irreversible inhibitors on enzyme function?

They permanently inactivate the enzyme. Signup and view all the answers

What is the significance of measuring initial velocity v0 in enzyme kinetics?

It allows calculation of kinetic parameters without substrate depletion. Signup and view all the answers

Which type of inhibition is characterized by an inhibitor binding to an allosteric site?

Noncompetitive inhibition Signup and view all the answers

Which of the following is a characteristic of competitive inhibitors?

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

What is the effect of a noncompetitive inhibitor on Km?

It has no effect on Km Signup and view all the answers

What can be inferred from a high Km value?

The enzyme has a low affinity for the substrate. Signup and view all the answers

What type of curve does a plot of 1/ v0 versus 1/[S] produce?

Linear Signup and view all the answers

Which of the following is a property of irreversible inhibitors?

They permanently alter the enzyme's structure. Signup and view all the answers

What happens to enzyme activity at extreme pH levels?

It can lead to denaturation. Signup and view all the answers

Which of the following statements is true regarding enzyme kinetics?

Kinetic parameters can vary with environmental conditions. Signup and view all the answers

Lecture 25 – Enzyme kinetics

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