Enzyme Structure and Components

Enzyme Components

• Apoenzyme: Protein component of an enzyme
• Cofactor: Nonprotein component of an enzyme
• Coenzyme: Organic cofactor
• Holoenzyme: Apoenzyme plus cofactor

Electron Carriers

• Assist enzymes in their functions
• Examples: NAD+, NADP+, FAD, Coenzyme A

Enzyme Classification

• Oxidoreductase: Catalyze oxidation-reduction reactions
• Transferase: Transfer functional groups
• Hydrolase: Catalyze hydrolysis reactions
• Lyase: Remove atoms without hydrolysis
• Isomerase: Rearrange atoms
• Ligase: Join molecules, using ATP

Factors Influencing Enzyme Activity

• Temperature:
  • Optimal range: Enzymes function best at a specific temperature range
  • High temperature: Increases activity up to a point, but extreme heat denatures enzymes
  • Low temperature: Slows down enzyme activity without causing denaturation
• pH:
  • Optimal pH: Each enzyme has an optimal pH where it is most active
  • Deviation: Changes in pH can alter enzyme structure and function, potentially leading to denaturation
• Substrate Concentration:
  • Low concentration: Increasing substrate levels boost enzyme activity
  • Saturation point: Beyond a certain concentration, enzyme activity plateaus as all active sites are occupied

Inhibitors

• Competitive Inhibitors: Compete with the substrate for the active site; effect can be reduced by increasing substrate concentration
• Non-Competitive Inhibitors: Bind elsewhere on the enzyme, changing its shape and reducing activity
• Uncompetitive Inhibitors: Bind only to the enzyme-substrate complex, lowering both the reaction rate and substrate affinity
• Allosteric Inhibitors: Bind to an allosteric site, causing conformational changes that decrease enzyme activity

Energy Production

• Metabolism: The sum of the chemical reactions in an organism
• Catabolism: Provides energy and building blocks for anabolism; involves degradative reactions that are generally hydrolytic, exergonic, and provide energy and building blocks
• Anabolism: Uses energy and building blocks to build large molecules; involves biosynthetic reactions that are generally dehydration synthesis, endergonic, and require energy

Role of ATP in Coupling Reactions

• ATP is an intermediate between catabolism and anabolism
• ATP is generated in catabolic reactions and used in anabolic reactions

Learn about the different components of enzymes, including apoenzymes, cofactors, and coenzymes, and how they interact to facilitate chemical reactions. Discover the role of electron carriers in assisting enzymes.