Biochemistry: Enzyme Action Mechanism

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Questions and Answers

What is one way that enzymes accelerate chemical reactions?

By bringing substrates into close proximity (correct)

By increasing the concentration of substrates

By inhibiting the reverse reaction

By reducing the temperature of the reaction

What happens to the enzyme after a reaction is completed?

It cannot bind to another substrate

It gets consumed along with the substrate

It changes permanently

It remains unchanged (correct)

In what way does the induced fit model relate to enzyme activity?

It results in a conformational change in the enzyme (correct)

It allows the substrate to bind without any changes

It inhibits substrate binding

It maintains the enzyme's original shape

At equilibrium during an enzyme-catalyzed reaction, what is true about the forward and reverse reactions?

Both reactions occur at equal rates Signup and view all the answers

Which mechanism describes how the binding of the substrate affects the enzyme's shape?

Strain and Distortion Mechanism Signup and view all the answers

What is a consequence of the high concentration of product in an enzyme reaction mixture?

It can potentially halt the forward reaction Signup and view all the answers

Why is it stated that enzyme-catalyzed reactions are theoretically reversible?

Because reactions can proceed both ways at equilibrium Signup and view all the answers

What role does the catalytic group play in enzyme function?

It facilitates the breakdown of the substrate's bonds Signup and view all the answers

What is the primary role of enzymes in biochemical reactions?

To accelerate the rate of reactions by lowering activation energy Signup and view all the answers

Which statement accurately describes the transition state in enzyme reactions?

It is a temporary and unstable state of the enzyme-substrate complex. Signup and view all the answers

What type of catalysis involves the active site of an enzyme acting as a proton donor?

General acid-base catalysis Signup and view all the answers

Why do some enzymes form unstable enzyme-substrate complexes?

To allow for further reactions to produce final products Signup and view all the answers

What defines the activation energy in enzymatic reactions?

The energy required to initiate the transition state Signup and view all the answers

Which of the following best describes covalent catalysis?

Enzymes form temporary covalent bonds with substrates to assist reactions. Signup and view all the answers

How does the free energy of activation relate to catalysis?

Enzymes lower the free energy of activation, increasing reaction rates. Signup and view all the answers

What is one effect of enzyme catalysis in reactions?

It allows for the reaction to occur at lower temperatures. Signup and view all the answers

What is the role of a catalyst in a chemical reaction?

To lower the energy of activation for the reaction Signup and view all the answers

What happens to the enzyme after a product is formed?

It is free to combine with another substrate molecule Signup and view all the answers

Which statement about the energy of activation is correct?

It is the energy needed to reach the transition state Signup and view all the answers

How does the presence of an enzyme affect the reaction's overall free energy change?

It does not alter the overall free energy change Signup and view all the answers

What is the transient state formed when a substrate combines with a catalyst called?

Activated complex Signup and view all the answers

What must the substrate possess for a reaction to occur?

Sufficient energy to reach the transition state Signup and view all the answers

In the context of enzyme-catalyzed reactions, what is meant by 'transition state'?

The point at which the chemical bonds are breaking and forming Signup and view all the answers

What does the energy required to bring all molecules in one gram mole to a given state represent?

Free energy of activation Signup and view all the answers

What is formed when an enzyme binds with a substrate?

Enzyme-substrate complex Signup and view all the answers

Which component of an enzyme specifically binds to the substrate during the catalytic process?

Catalytic site Signup and view all the answers

What type of interaction primarily stabilizes the enzyme-substrate complex?

Hydrogen bonds Signup and view all the answers

In terms of size comparison, how do enzymes relate to their substrates?

Enzymes are much larger than substrates. Signup and view all the answers

What is the purpose of the active site of an enzyme?

To bind the substrate and catalyze reactions Signup and view all the answers

Which feature distinguishes the active center of an enzyme?

It contains specific sites that bind substrates. Signup and view all the answers

What is the role of transitional (intermediate) compounds in enzyme activity?

They are formed during the catalytic process. Signup and view all the answers

Which type of amino acid group is important for the active sites of enzymes?

Amino acids with sulfhydryl groups Signup and view all the answers

What is the primary role of the enzyme-substrate complex?

To transform the substrate into a product. Signup and view all the answers

Which statement accurately describes the enzyme's function after the substrate is transformed?

The enzyme returns to its original form. Signup and view all the answers

What key interaction is compared to the relationship between an enzyme and its substrate?

A lock and key. Signup and view all the answers

According to the Michaelis-Menten theory, what is formed when an enzyme combines with its substrate?

Enzyme-substrate complex. Signup and view all the answers

Which amino acids are mentioned as present at the active site of enzymes?

Tyrosine and lysine. Signup and view all the answers

What is the immediate product of the reaction catalyzed by the enzyme after the enzyme-substrate complex is formed?

Product. Signup and view all the answers

In enzyme kinetics, what does the term 'active site' refer to?

The specific region of the enzyme where substrate binding occurs. Signup and view all the answers

What describes the process of the enzyme returning to its original state after catalyzing a reaction?

Enzyme regeneration. Signup and view all the answers

Study Notes

Enzyme Action Mechanism

Enzymes act by forming a temporary complex with the substrate
The enzyme-substrate complex (ES) lowers the activation energy needed for the reaction
The substrate is converted into product(s)
The enzyme is unchanged after the reaction

Enzyme-Substrate Complex (ES)

The enzyme and substrate bind at the active site
The binding involves specific interactions (e.g., hydrogen bonds, ionic interactions)
The binding causes the substrate's shape to change slightly (induced fit model)

Michaelis-Menten Equation

Describes the relationship between substrate concentration, enzyme concentration and reaction rate
Defines the maximum velocity (Vmax) and the Michaelis constant (Km)
Km represents the substrate concentration at which the reaction rate is half of Vmax

Factors Affecting Enzyme Activity

Temperature: Optimum temperature exists, higher temperatures denature enzymes
pH: Enzymes have optimal pH values
Substrate concentration: Increasing substrate amount increases reaction rate to Vmax
Enzyme concentration: Higher enzyme concentration, faster reaction to Vmax
Inhibitors: Substances can inhibit enzyme activity (competitive or non-competitive)

Enzyme Structure and Function

Enzymes are proteins with a specific 3D structure
The active site is a crucial region for substrate binding
The active site's shape and chemical properties are unique to each enzyme, allowing it to catalyze only particular reactions
The active site's structure allows interactions with the substrate, facilitating the reaction

Enzyme Catalysis Mechanisms

Enzymes lower activation energy by bringing substrates together
Proximity: Orienting molecules properly to facilitate bonding
Straining the substrate: Altering substrate shape for easier bond breaking
General acid/base catalysis: Enzyme donates/accepts protons to alter substrate
Covalent catalysis: Enzyme forms temporary covalent bonds with substrate to increase reaction rate
Induced fit: the enzyme's active site molds to the substrate's shape

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Description

Explore the fascinating world of enzyme action mechanisms in biochemistry. This quiz covers the enzyme-substrate complex, the Michaelis-Menten equation, and factors affecting enzyme activity. Test your understanding of how enzymes function and their importance in biological reactions.