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What term is used to describe the initial rate of an enzyme-catalyzed reaction?
Which parameter can be calculated from the slope of a Hanes plot in enzyme kinetics?
What does the turnover number (kcat) represent in enzyme kinetics?
In which units is Vmax typically expressed in enzyme kinetics?
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What is the term for the enzyme-substrate complex in enzyme kinetics?
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Which parameter represents the substrate concentration at half of Vmax in Michaelis-Menten kinetics?
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What factor can be used to determine the kcat value of an enzyme?
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What does a steeper line in a Lineweaver-Burk plot indicate about enzyme kinetics?
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What does a lower intercept on the y-axis of a Lineweaver-Burk plot suggest about competitive inhibition?
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______ determine Ki via Hanes
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Analyze experimental enzyme kinetics data from scientific papers. Know the productivity terms. Understand productivity metrics. Describe principles for immobilized enzymes. Know advantages vs. disadvantages of immobilized enzymes. Calculate immob. kinetics basics. Describe a few important technical, industrial enzyme applications and processes. Know about enzymatic depolymerization kinetics starch, pectin. Enzyme activity? Initial rate? Constant rate v depends on Etot. Rate, vi ~ enzyme concentration! v = k 2 E tot [S] [S] + K M. Recap enzyme activity units. Parameter Calculation Typical units. Activity (Act) ΔS/Δt at/or near Vmax. U (µmole/min), katal (mole/s) Activity conc. Act/vol. or Act/mass. U/mL, U/mg, [nkat/mL, nkat/mg]. Specific Activity Act/massprotein. U/g, U/mg, kat/g, nkat/mg. Vmax Hanes (S/v versus S) M×s-1 or mole×s-1 [or µM×min-1] v (rate) ΔS/Δt (or from ΔP/Δt) M×s-1 or mole×s-1 [or µM×min-1]. _______ kcat, k2, turnover no. Vmax/Etot (Vmax/E0) s-1 KM Hanes (S/v versus S) M, g/L, (mM or µM) Etot or E0 [Efree] + [ES] +...moles/L or mg/L or g/L NB !v (rate) may also be calculated from: nS/Δt when nS is no.
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Calculate ______ to determine Ki via Hanes
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The Vmax in Hanes plot is typically expressed in M×s-1 or mole×s-1 [or µM×min-1]. The rate v depends on Etot. Rate, vi ~ enzyme concentration! v = k 2 E tot [S] [S] + K M. Recap enzyme activity units. Parameter Calculation Typical units. Activity (Act) ΔS/Δt at/or near Vmax is in U (µmole/min) or katal (mole/s). Specific Activity Act/massprotein is in U/g, U/mg, kat/g, nkat/mg. ______ Hanes (S/v versus S) is used to calculate KM
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Enzyme activity depends on the rate, vi ~ enzyme concentration! v = k 2 E tot [S] [S] + K M. Recap enzyme activity units. Parameter Calculation Typical units. Activity (Act) ΔS/Δt at/or near Vmax is in U (µmole/min) or katal (mole/s). Activity conc. Act/vol. or Act/mass is in U/mL, U/mg, [nkat/mL, nkat/mg]. Specific Activity Act/massprotein is in U/g, U/mg, kat/g, nkat/mg. Vmax Hanes (S/v versus S) is typically expressed in M×s-1 or mole×s-1 [or µM×min-1]. ______ Hanes (S/v versus S) is used to calculate Vmax/Etot (Vmax/E0)
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The enzyme-substrate complex in enzyme kinetics is also known as ______
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______ can be calculated from the slope of a Hanes plot in enzyme kinetics
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The turnover number (kcat) represents the ______ of an enzyme
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In enzyme kinetics, the initial rate of an enzyme-catalyzed reaction is described by the term ______
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A steeper line in a Lineweaver-Burk plot indicates a ______ enzyme kinetics
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The lower intercept on the y-axis of a Lineweaver-Burk plot suggests ______
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Study Notes
Enzyme Kinetics Concepts
- Reaction rate (v) relies on substrate concentration ([S]), enzyme concentration ([E]), and Michaelis-Menten kinetics.
- Michaelis-Menten equation:
[ v_0 = \frac{V_{max} \cdot [S]}{[S] + K_M} ] - At high substrate concentration, the formula simplifies since [S] >> [KM], giving:
[ v_0 \approx V_{max} ]
Determination of Kinetic Constants
- Vmax is the maximum reaction rate, achieved when all enzyme active sites are saturated with substrate.
- KM is the substrate concentration at which the reaction rate is half of Vmax; reflects enzyme affinity for substrate.
- The Hanes or Woolf plot offers a method to determine Vmax and KM with better error distribution:
[ \frac{[S]}{v} = \frac{1}{V_{max}} \cdot [S] + \frac{K_M}{V_{max}} ]
Integrated Rate Equations
- Integrated rate equations express the relationship between substrate concentration changes over time.
- For progress curves:
[ \frac{1}{[S_0]} = \frac{V_{max}}{[S_0]} + K_M \left(1 + \frac{K_M}{[S_0]}\right) ]
Effects of Temperature on Enzyme Activity
- Arrhenius equation relates the temperature with reaction rate. Activation energy (Ea) affects rate via temperature:
[ v = Ae^{-\frac{E_a}{RT}} ] - The Q10 rule evaluates temperature effects on reaction rates:
[ Q_{10} = \frac{k_{cat,T2}}{k_{cat,T1}} ]
Enzyme Inhibition
- Competitive inhibition increases the apparent KM (KMapp) while Vmax remains unchanged.
- Inhibitor (I) competes with the substrate (S) for enzyme binding, modeled as:
[ v = \frac{V_{max} \cdot [S]}{[S] + K_M(1 + \frac{[I]}{K_i})} ] - The dissociation constant (Ki) quantifies inhibitor binding affinity.
Starch Hydrolysis
- Enzymatic hydrolysis can occur through different mechanisms: endo- and exo-action.
- Glucoamylase, an important enzyme in starch breakdown, is also known as amyloglucosidase (AMG).
Summary of Concepts
- Understanding kinetics involves grasping how substrate concentration affects reaction rates, how to determine Vmax and KM, and considering influences such as temperature and inhibition.
- Plotting methods—like the Hanes plot—help in visualizing and estimating enzyme kinetics effectively.
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Description
This quiz covers topics related to enzyme kinetics equations such as Briggs-Haldane equation, Michaelis-Menten equation, determination of constants Vmax and KM, and the integrated rate equation. Test your knowledge on enzyme kinetics with this quiz!
