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Questions and Answers
What happens to the rate of an enzyme-catalyzed reaction when the substrate concentration becomes the limiting factor?
What happens to the rate of an enzyme-catalyzed reaction when the substrate concentration becomes the limiting factor?
What is the relationship between enzyme concentration and reaction rate when substrate concentration is not limiting?
What is the relationship between enzyme concentration and reaction rate when substrate concentration is not limiting?
What is the significance of the Q10 value in enzyme-controlled reactions?
What is the significance of the Q10 value in enzyme-controlled reactions?
Why do cold-water fish die at 30°C?
Why do cold-water fish die at 30°C?
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What happens to most enzymes at 70°C?
What happens to most enzymes at 70°C?
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What is the pH range preferred by most enzymes for optimal activity?
What is the pH range preferred by most enzymes for optimal activity?
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What induces a change in the enzyme's conformation when it combines with a substrate?
What induces a change in the enzyme's conformation when it combines with a substrate?
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What is the primary function of the active site of an enzyme?
What is the primary function of the active site of an enzyme?
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In the Michaelis-Menten equation, what does the KS constant stand for?
In the Michaelis-Menten equation, what does the KS constant stand for?
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According to Michaelis and Menten's assumptions, what is a key aspect of the enzymatic reaction?
According to Michaelis and Menten's assumptions, what is a key aspect of the enzymatic reaction?
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What is the primary focus of the Michaelis-Menten equation?
What is the primary focus of the Michaelis-Menten equation?
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What is one assumption made by Michaelis and Menten about enzyme reactions?
What is one assumption made by Michaelis and Menten about enzyme reactions?
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What is the Michaelis-Menten constant denoted by in the given equation?
What is the Michaelis-Menten constant denoted by in the given equation?
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How is enzyme activity commonly expressed?
How is enzyme activity commonly expressed?
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Why does the rate of an enzyme-catalyzed reaction increase with an increase in substrate concentration?
Why does the rate of an enzyme-catalyzed reaction increase with an increase in substrate concentration?
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In what scenario would the initial rate of an enzyme-catalyzed reaction be proportional to the concentration of enzyme ([E])?
In what scenario would the initial rate of an enzyme-catalyzed reaction be proportional to the concentration of enzyme ([E])?
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How does an increase in enzyme concentration affect the reaction rate?
How does an increase in enzyme concentration affect the reaction rate?
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At what point does an enzyme become saturated in terms of substrate concentration?
At what point does an enzyme become saturated in terms of substrate concentration?
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What is the primary role of inorganic metal ions in enzyme catalysis?
What is the primary role of inorganic metal ions in enzyme catalysis?
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Which coenzyme is responsible for transferring acyl groups during metabolic reactions?
Which coenzyme is responsible for transferring acyl groups during metabolic reactions?
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What is the function of a transient carrier coenzyme in biochemical reactions?
What is the function of a transient carrier coenzyme in biochemical reactions?
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Which vitamin serves as a dietary precursor for mammals and is essential for various carboxylation reactions?
Which vitamin serves as a dietary precursor for mammals and is essential for various carboxylation reactions?
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What is the main function of inhibitors on enzyme activities?
What is the main function of inhibitors on enzyme activities?
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Which inorganic element acts as a cofactor for the enzyme carbonic anhydrase?
Which inorganic element acts as a cofactor for the enzyme carbonic anhydrase?
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What is a coenzyme when it comes to enzyme cofactors?
What is a coenzyme when it comes to enzyme cofactors?
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Which type of cofactor is referred to as a prosthetic group?
Which type of cofactor is referred to as a prosthetic group?
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What is the composition of a holoenzyme?
What is the composition of a holoenzyme?
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In enzyme catalysis, coenzymes often function as what?
In enzyme catalysis, coenzymes often function as what?
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What role does NAD play in certain oxidations/reductions?
What role does NAD play in certain oxidations/reductions?
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What distinguishes coenzymes from other enzyme cofactors?
What distinguishes coenzymes from other enzyme cofactors?
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Study Notes
Enzyme Catalysed Reactions
- The rate of an enzyme-catalysed reaction is directly proportional to the enzyme concentration when the substrate concentration is not limiting.
- Increasing enzyme concentration will increase the rate of reaction until the substrate concentration becomes the limiting factor.
Effect of Temperature on Velocity
- Enzymes have an optimal temperature, with a balance between the Q10 (temperature coefficient) and denaturation.
- Q10 is the increase in reaction rate with a 10°C rise in temperature, with a typical value of 2-3 for chemical reactions.
- Most enzymes are fully denatured at 70°C, but some can withstand high temperatures up to 100°C.
Effect of pH Value on Velocity
- The pH optimum varies for different enzymes, with most having a neutral pH (6-8).
- When a substrate combines with an enzyme, it induces a change in the enzyme's conformation, making the chemical environment suitable for the reaction.
Michaelis-Menten Equation
- The Michaelis-Menten equation describes the velocity of enzymatic reactions, with the equation: VO = Vmax[S] / Km + [S]
- VO is the initial velocity of the reaction, Vmax is the maximum velocity, Km is the Michaelis-Menten constant, and [S] is the substrate concentration.
Enzyme Velocity and Activity
- Enzyme activity is expressed by the initial rate (V0) of the reaction being catalyzed.
- Enzyme activity is measured in moles of substrate converted to product per unit time.
- Velocity decreases as time increases due to factors such as substrate depletion, product inhibition, pH change, and cofactor depletion.
Effect of Substrate Concentration
- An increase in substrate concentration increases the rate of enzyme-catalysed reaction, but eventually reaches a point of saturation where further increases have no effect.
Effect of Enzyme Concentration
- The initial rate of an enzyme-catalysed reaction is proportionate to the concentration of enzyme.
Coenzymes and Cofactors
- Coenzymes are organic molecules that are derivatives of vitamins and act as transient carriers of specific atoms or functional groups.
- Examples of coenzymes include Coenzyme A, Flavin adenine dinucleotide, and Nicotinamide adenine dinucleotide.
- Inorganic metal ions such as Cu2+, Fe2+/Fe3+, K+, Mg2+, Mn2+, Mo, Ni2+, Se, and Zn2+ serve as cofactors by forming coordination bonds with side chains at the active site and with the substrate.
Inhibition of Enzyme Activities
- Inhibitors are molecules that act directly on an enzyme to lower its catalytic rate, often at low concentrations and with specificity.
- Cofactors can be organic compounds (coenzymes) or inorganic groups (metal ions).
- Prosthetic groups are organic or inorganic compounds that are tightly bound to the apoenzyme.
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Description
Learn about how substrates combine with enzymes to induce a change in conformation, create a suitable chemical environment for reactions, and lower the activation energy. Explore the Michaelis-Menten equation and different mechanisms of enzyme reactions proposed by biochemists.
