Podcast
Questions and Answers
What is the relationship between enzyme rate and substrate concentration?
What is the relationship between enzyme rate and substrate concentration?
- Enzyme rate increases with increasing substrate concentration, but reaches a maximum velocity when the enzyme is saturated with substrate. (correct)
- Enzyme rate decreases with increasing substrate concentration, reaching a minimum velocity when the enzyme is saturated with substrate.
- Enzyme rate is inversely proportional to substrate concentration.
- Enzyme rate remains constant regardless of substrate concentration.
What is the role of regulatory enzymes in metabolic pathways?
What is the role of regulatory enzymes in metabolic pathways?
- Regulatory enzymes catalyze the fastest step in the pathway, affecting the rate of the entire pathway.
- Regulatory enzymes have no significant impact on the rate of the metabolic pathway.
- Regulatory enzymes only regulate the initial steps of a metabolic pathway.
- Regulatory enzymes usually catalyze the rate-limiting step in the pathway, affecting the rate of the entire pathway. (correct)
What does the Michaelis–Menten equation describe?
What does the Michaelis–Menten equation describe?
- The relationship between initial velocity of a reaction, substrate concentration, maximum velocity, and the substrate concentration at which the initial velocity is half of the maximum velocity. (correct)
- The relationship between enzyme activity and pH levels.
- The relationship between enzyme rate and the concentration of enzyme inhibitors.
- The relationship between enzyme concentration and substrate concentration.
What is the function of the regulatory enzyme in a metabolic pathway?
What is the function of the regulatory enzyme in a metabolic pathway?
How do changes in physiologic state, time of eating, environment, diet, or age affect enzyme rates?
How do changes in physiologic state, time of eating, environment, diet, or age affect enzyme rates?
What is the impact of substrate concentration on enzyme rate?
What is the impact of substrate concentration on enzyme rate?
Which type of enzyme inhibitor binds to a site other than the catalytic site, causing conformational changes that affect enzyme activity?
Which type of enzyme inhibitor binds to a site other than the catalytic site, causing conformational changes that affect enzyme activity?
What type of modification can regulate enzyme activity through the addition of a phosphate group?
What type of modification can regulate enzyme activity through the addition of a phosphate group?
Which process involves the activation of target proteins through reversible binding by monomeric G-proteins?
Which process involves the activation of target proteins through reversible binding by monomeric G-proteins?
What type of regulation occurs when the end product of a pathway controls its own rate of synthesis?
What type of regulation occurs when the end product of a pathway controls its own rate of synthesis?
How are some enzymes initially synthesized before being activated by proteolysis?
How are some enzymes initially synthesized before being activated by proteolysis?
In what way can enzyme concentration be regulated?
In what way can enzyme concentration be regulated?
Which type of inhibitor alters the intersection on the y-axis in Lineweaver-Burk plots?
Which type of inhibitor alters the intersection on the y-axis in Lineweaver-Burk plots?
What type of inhibition occurs when an inhibitor binds to the enzyme and enzyme-substrate complex with the same affinity?
What type of inhibition occurs when an inhibitor binds to the enzyme and enzyme-substrate complex with the same affinity?
Which type of inhibition prevents enzymes from generating a product faster than it can be used?
Which type of inhibition prevents enzymes from generating a product faster than it can be used?
What is a mechanism through which enzyme regulation can be achieved?
What is a mechanism through which enzyme regulation can be achieved?
What can rapidly change an enzyme from an inactive form to an active conformation?
What can rapidly change an enzyme from an inactive form to an active conformation?
In which model is the path from low-affinity to high-affinity conformation preferred?
In which model is the path from low-affinity to high-affinity conformation preferred?
What is the relationship between substrate concentration and enzyme velocity when the substrate concentration is below Km?
What is the relationship between substrate concentration and enzyme velocity when the substrate concentration is below Km?
How is Km related to the dissociation constant, Kd?
How is Km related to the dissociation constant, Kd?
What does the Lineweaver–Burk transformation visually determine from a plot of 1/vi versus 1/S?
What does the Lineweaver–Burk transformation visually determine from a plot of 1/vi versus 1/S?
Which type of hexokinase has a low Km for glucose?
Which type of hexokinase has a low Km for glucose?
What is the role of hepatic glucokinase in glucose metabolism?
What is the role of hepatic glucokinase in glucose metabolism?
What is MODY, a rare genetic form of diabetes mellitus, caused by?
What is MODY, a rare genetic form of diabetes mellitus, caused by?
In the Lineweaver-Burk transformation, when [S] is infinite, what value does 1/[S] equal to, and where does the line cross the ordinate (y-axis)?
In the Lineweaver-Burk transformation, when [S] is infinite, what value does 1/[S] equal to, and where does the line cross the ordinate (y-axis)?
What is the slope of the line in the Lineweaver-Burk transformation, and what does it represent?
What is the slope of the line in the Lineweaver-Burk transformation, and what does it represent?
What does Vmax represent in enzyme kinetics?
What does Vmax represent in enzyme kinetics?
How is Vmax often expressed, and is it dependent on enzyme concentration?
How is Vmax often expressed, and is it dependent on enzyme concentration?
What type of plot is typically shown by GK (glucokinase) in comparison to hexokinase I?
What type of plot is typically shown by GK (glucokinase) in comparison to hexokinase I?
How do noncompetitive inhibitors affect enzyme activity?
How do noncompetitive inhibitors affect enzyme activity?
Study Notes
Enzyme Kinetics and Inhibition
- Lineweaver–Burk transformation converts Michaelis–Menten equation to a straight line of the form y = mx + b
- When [S] is infinite, 1/[S] = 0, and the line crosses the ordinate (y-axis) at 1/v = 1/Vmax
- The slope of the line is Km/Vmax and where the line intersects the abscissa (x-axis), 1/[S] = –1/Km
- Rate of reaction is directly proportional to enzyme concentration
- Vmax is often expressed as product produced per minute per milligram of enzyme and is independent of enzyme concentration
- Comparison between hexokinase I and GK, with GK showing a slightly sigmoidal plot
- Multisubstrate reactions affect the rate equation and apparent value of Km (Km,app) depends on the concentration of cosubstrate or product present
- Equations for the initial velocity of an enzyme-catalyzed reaction provide useful parameters for describing or comparing enzymes
- Michaelis–Menten model is inapplicable to multisubstrate enzymes and enzymes present in higher concentration than their substrates
- Reversible inhibition within the active site can alter enzyme activity through compounds binding in the active site
- Competitive inhibitors "compete" with a substrate for binding at the enzyme’s substrate-recognition site
- Noncompetitive inhibitors do not compete with a substrate for its binding site, and uncompetitive inhibition is almost never encountered in medicine
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Description
Test your knowledge of enzyme kinetics and inhibition with this quiz covering topics such as Lineweaver–Burk transformation, Michaelis–Menten equation, enzyme concentration, Vmax, multisubstrate reactions, and reversible inhibition. See how well you understand the concepts and applications of enzyme kinetics.
