Enzymes

What does ΔG° symbolize in the context of enzymatic reactions? ΔG° symbolizes the standard free energy change at pH 7.

What types of reactions do lyases catalyze? Lyases remove atoms to form double bonds or add atoms to double bonds.

What happens to the equilibrium constant as a reaction becomes more exergonic? The equilibrium constant becomes larger as the reaction becomes more exergonic.

What are enzymes and how do they function as catalysts in biochemical reactions? Enzymes are protein catalysts that accelerate biochemical reactions, lowering the activation energy required for the reaction to occur.

How do transferases function in enzyme activity? Transferases function by moving functional groups from one molecule to another.

What role do proteolytic enzymes play in biochemical reactions? Proteolytic enzymes catalyze the hydrolysis of peptide bonds, breaking down proteins into smaller peptides or amino acids.

What is an example of a reaction that requires an enzyme? The reaction of adding a molecule of water to carbon dioxide requires the enzyme carbonic anhydrase.

What does a positive ΔG indicate about a reactions feasibility? A positive ΔG indicates that a reaction is endergonic and will not occur spontaneously.

What are the six major classes of enzymes and their functions? 1. Oxidoreductases - catalyze redox reactions. 2. Transferases - move functional groups. 3. Hydrolyases - cleave bonds with water. 4. Lyases - form/remove double bonds. 5. Isomerases - rearrange molecules. 6. Ligases - join molecules using ATP.

What is the symbol for the change in free energy during a reaction? The change in free energy is symbolized by ΔG.

How does Gibbs free energy relate to enzyme catalysis? Gibbs free energy (ΔG) measures the energy change during a reaction, and enzymes do not alter this ΔG.

How do enzymes facilitate the formation of the transition state? Enzymes lower the activation energy needed to reach the transition state, thus accelerating the reaction.

What is the difference between a holoenzyme and an apoenzyme? A holoenzyme is an active enzyme with its cofactor, while an apoenzyme is the inactive form without the cofactor.

What is activation energy and how is it related to enzymes? Activation energy (ΔG‡) is the energy required to form the transition state, which enzymes help to lower.

How do isomerases alter molecular structures? Isomerases rearrange the functional groups within a molecule.

What is the role of hydrolyases in biochemical reactions? Hydrolyases cleave bonds in molecules by adding water.

How do trypsin and thrombin differ in their enzyme specificity? Trypsin cleaves on the carboxyl side of arginine and lysine, while thrombin specifically cleaves Arg-Gly bonds in certain sequences.

How much can enzymes accelerate the rate of a reaction? Enzymes can accelerate the rate of a reaction by factors of a million or more.

How do enzymes affect the ΔG of a reaction? Enzymes do not change the ΔG of a reaction; they speed up the reaction without altering the energy difference.

What are substrates in the context of enzyme-catalyzed reactions? Substrates are the reactants involved in enzyme-catalyzed reactions.

What are the two main classes of cofactors? The two main classes of cofactors are coenzymes (organic molecules) and metal ions.

What are oxidoreductases and what types of reactions do they catalyze? Oxidoreductases catalyze oxidation-reduction reactions, involving the transfer of electrons.

What is hydrolysis and how is it related to enzymes? Hydrolysis is the breaking of a chemical bond by the addition of a water molecule, and it is facilitated by enzymes in various biochemical processes.

What is the significance of a negative ΔG in biochemical reactions? Negative ΔG indicates that a reaction is exergonic and can proceed without energy input.

Why cant enzymes alter the reaction equilibrium despite affecting the reaction rate? Enzymes cannot change the free energy difference between products and reactants, which determines equilibrium.

What is the function of ligases in enzymatic reactions? Ligases join two molecules together, usually using ATP as energy.

What conditions indicate a reaction is spontaneous based on ΔG? A reaction is spontaneous if ΔG is negative.

How is the standard free energy change related to the equilibrium constant of a reaction? The standard free energy change (ΔG°) is related to the equilibrium constant (Keq) by the equation ΔG° = -RT ln(Keq).

What is a transition state in enzyme-catalyzed reactions? A transition state is a molecular form that is neither substrate nor product, during which the reaction occurs.

What are cofactors and why do some enzymes require them? Cofactors are small molecules needed by some enzymes for activity; they enhance enzyme function.