Catalysis and Enzymes Quiz

Catalysis

• 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

Enzymatic Kinetics

• 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

Isoenzymes

• 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

Enzyme Inhibition

• 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

Proteolysis

• 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

Test your knowledge of enzymes, catalysis, and their roles in biological reactions. Learn about enzymatic kinetics, isoenzymes, enzyme inhibition, and proteolysis.