Catalysis and Enzymes Quiz

Study Notes

Enzymes are biological catalysts that speed up chemical reactions without being consumed by the reaction
They lower the activation energy required for a reaction to occur, allowing the reaction to proceed faster
Enzymes do not alter the equilibrium of the reaction, only the rate at which it reaches equilibrium
Catalysis involves the formation of an enzyme-substrate complex, which then breaks down to form the product

Study of the rates of enzyme-catalyzed reactions
Key factors that influence enzyme kinetics:
- Substrate concentration
- Enzyme concentration
- Temperature
- pH
Michaelis-Menten equation describes the kinetics of enzyme-catalyzed reactions
- Km (Michaelis constant) is the substrate concentration at which the reaction rate is half of the maximum rate
- Vmax (maximum reaction rate) is the maximum rate of the reaction at saturating substrate concentrations

Multiple forms of an enzyme that catalyze the same reaction
Differ in their amino acid sequence, kinetics, or other properties
Isoenzymes can have different:
- Optimal temperatures
- Optimal pH ranges
- Substrate specificities
- Inhibitor sensitivities
Isoenzymes can be used to:
- Distinguish between different tissues or cell types
- Diagnose diseases
- Monitor treatment responses

Reversible inhibition:
- Competitive inhibition: inhibitor binds to the active site, competing with the substrate
- Uncompetitive inhibition: inhibitor binds to an allosteric site, changing the enzyme's shape and reducing its activity
- Non-competitive inhibition: inhibitor binds to an allosteric site, reducing the enzyme's activity without competing with the substrate
Irreversible inhibition:
- Covalent modification of the enzyme, such as phosphorylation or proteolysis
- Inactivation of the enzyme, such as through oxidation or reduction

Breakdown of proteins into smaller peptides or amino acids
Can be catalyzed by enzymes called proteases
Types of proteolysis:
- Endoproteolysis: cleavage within a protein sequence
- Exoproteolysis: cleavage at the N- or C-terminus of a protein
Proteolysis can:
- Activate or inactivate enzymes
- Regulate protein function
- Degrade damaged or misfolded proteins
- Play a role in disease pathogenesis, such as in cancer or neurodegeneration