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What does Kcat represent in enzyme kinetics?
What does Kcat represent in enzyme kinetics?
- The maximum rate at which an enzyme can convert substrate to product
- The affinity of an enzyme for its substrate
- The concentration of free enzyme at steady state
- The rate of ES complex formation per unit time (correct)
What is indicated by the term 'steady state' in enzyme kinetics?
What is indicated by the term 'steady state' in enzyme kinetics?
- The rate of formation and breakdown of the ES complex balances out (correct)
- The concentration of the substrate remains constant over time
- The enzyme concentration varies throughout the reaction
- The substrate is fully consumed by the enzyme
Which assumption must be met for Michaelis-Menten kinetics to apply?
Which assumption must be met for Michaelis-Menten kinetics to apply?
- The enzyme concentration needs to be greater than the substrate concentration
- The reaction reaches its final product before measuring initial rates
- The enzyme concentration must be less than the substrate concentration (correct)
- All substrate must bind to the enzyme simultaneously
What does the term Km measure in the context of enzyme kinetics?
What does the term Km measure in the context of enzyme kinetics?
How is Vmax affected in enzymatic reactions?
How is Vmax affected in enzymatic reactions?
What is the Vmax for the uninhibited enzyme as given?
What is the Vmax for the uninhibited enzyme as given?
What is the value of Km for the uninhibited enzyme?
What is the value of Km for the uninhibited enzyme?
If 10 nmol of enzyme is used in a 100 μL reaction, which formula helps in calculating kcat?
If 10 nmol of enzyme is used in a 100 μL reaction, which formula helps in calculating kcat?
In the provided content, what is the reaction volume stated for the enzyme activity?
In the provided content, what is the reaction volume stated for the enzyme activity?
What is the first step to find kcat as mentioned in the content?
What is the first step to find kcat as mentioned in the content?
How is Km represented in the context provided?
How is Km represented in the context provided?
What unit is used to express the Vmax in the provided content?
What unit is used to express the Vmax in the provided content?
What is the concentration of the enzyme in the solution if 10 nmol of enzyme is used in a 100 μL reaction?
What is the concentration of the enzyme in the solution if 10 nmol of enzyme is used in a 100 μL reaction?
What process do proteases use to cleave proteins?
What process do proteases use to cleave proteins?
Which of the following best describes hydrolysis in the context of proteases?
Which of the following best describes hydrolysis in the context of proteases?
What is a key characteristic of the catalytic trend in serine proteases?
What is a key characteristic of the catalytic trend in serine proteases?
What are the primary roles of nucleophiles and electrophiles during the reaction with proteases?
What are the primary roles of nucleophiles and electrophiles during the reaction with proteases?
Which amino acid residues are commonly involved in the catalytic mechanism of serine proteases?
Which amino acid residues are commonly involved in the catalytic mechanism of serine proteases?
What type of kinetics is exhibited by chymotrypsin?
What type of kinetics is exhibited by chymotrypsin?
What is the effect of a catalyst on the rate of a reaction involving hydrolysis by proteases?
What is the effect of a catalyst on the rate of a reaction involving hydrolysis by proteases?
In the context of proteolysis, what does the term 'acyl-enzyme' refer to?
In the context of proteolysis, what does the term 'acyl-enzyme' refer to?
What does the variable kat represent in the context provided?
What does the variable kat represent in the context provided?
What is the unit for the slope calculated in the content?
What is the unit for the slope calculated in the content?
At what concentration is Kat calculated to be 60,600 min?
At what concentration is Kat calculated to be 60,600 min?
What does Vmax represent in the equations provided?
What does Vmax represent in the equations provided?
What is the relation of kat to [C]T and [E]T in the equation for Vmax?
What is the relation of kat to [C]T and [E]T in the equation for Vmax?
How is specificity constant calculated according to the given information?
How is specificity constant calculated according to the given information?
What does the term 0.0606 x 10^-3 M/m denote?
What does the term 0.0606 x 10^-3 M/m denote?
Which of the following denotes a concentration conversion mentioned in the content?
Which of the following denotes a concentration conversion mentioned in the content?
What happens to enzyme activity when temperature increases?
What happens to enzyme activity when temperature increases?
What is the effect of competitive inhibitors on enzyme activity?
What is the effect of competitive inhibitors on enzyme activity?
What is the effect of uncompetitive inhibitors on Km and Vmax?
What is the effect of uncompetitive inhibitors on Km and Vmax?
Which type of inhibitor binds equally to the enzyme regardless of substrate presence?
Which type of inhibitor binds equally to the enzyme regardless of substrate presence?
What is observed in a double-reciprocal plot when a competitive inhibitor is present?
What is observed in a double-reciprocal plot when a competitive inhibitor is present?
What is the effect of noncompetitive inhibitors on Vmax?
What is the effect of noncompetitive inhibitors on Vmax?
How do irreversible inhibitors typically affect enzymes?
How do irreversible inhibitors typically affect enzymes?
What is the typical impact of a competitive inhibitor on the Km value?
What is the typical impact of a competitive inhibitor on the Km value?
What characteristic is unique to uncompetitive inhibitors compared to competitive inhibitors?
What characteristic is unique to uncompetitive inhibitors compared to competitive inhibitors?
What does a higher Km value indicate about an enzyme's affinity for a substrate?
What does a higher Km value indicate about an enzyme's affinity for a substrate?
Which type of inhibition occurs when an inhibitor binds to a site other than the active site?
Which type of inhibition occurs when an inhibitor binds to a site other than the active site?
What changes occur in the presence of a competitive inhibitor according to the Michaelis-Menten kinetics?
What changes occur in the presence of a competitive inhibitor according to the Michaelis-Menten kinetics?
What is indicated by a decrease in Vmax when an enzyme is inhibited?
What is indicated by a decrease in Vmax when an enzyme is inhibited?
Which of the following describes the behavior of noncompetitive inhibitors?
Which of the following describes the behavior of noncompetitive inhibitors?
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Study Notes
Uninhibited Enzyme
- The uninhibited enzyme's Vmax is 25 mM/s.
- The uninhibited enzyme's Km is 0.09 mg/mL.
Kcat Calculation
- The enzyme concentration is 10 nmol in a 100 μL reaction.
- The Kcat is calculated using the formula: Kcat = Vmax / [ET].
- The Kcat is 60,600 min.
Enzyme Kinetics
- Km is a measure of substrate affinity, representing the substrate's binding to the enzyme.
- Vmax is a measure of enzyme rate, dependent on enzyme concentration.
Enzyme Activity and Temperature
- Increased temperature initially increases enzyme rate, as it increases the stability of the protein/enzyme.
Enzyme Activity and Protonation/Deprotonation
- Enzyme activity depends on the protonation/deprotonation of specific groups, which can activate or deactivate the enzyme.
Inhibitors
- Competitive inhibitors bind to the active site, preventing substrate binding.
- Uncompetitive inhibitors bind to the enzyme-substrate complex, preventing product formation.
- Noncompetitive inhibitors bind to an allosteric site, affecting enzyme conformation and activity.
Double-Reciprocal Plot
- Double-reciprocal plots (Lineweaver-Burk plots) are used to represent enzyme kinetic data linearly.
- Competitive, uncompetitive, and noncompetitive inhibition can be distinguished by analyzing the changes in slope and y-intercept of the plot.
Irreversible Inhibitors
- Irreversible inhibitors typically form a covalent bond with the enzyme, permanently inactivating it.
Protease Kinetics
- Proteases cleave proteins by hydrolysis.
- Chymotrypsin demonstrates biphasic kinetics due to its acylation-deacylation mechanism.
Serine Protease Kinetics
- Serine proteases have an Asp-His-Ser catalytic triad.
- Kinetics follow a specific rate equation with specific Km and Vmax values.
- The Kcat for serine protease is 60,600 min.
- Specificity constant (Kcat/Km) is a measure of the enzyme's preference for a particular substrate.
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