Enzymes and Their Function

Enzymes

• Definition: Biological catalysts that speed up chemical reactions in living organisms without being consumed in the process.

• Structure:

  • Composed of proteins (most enzymes) or RNA (ribozymes).
  • Have a unique three-dimensional shape that is crucial for their function.

• Active Site:

  • Specific region where substrate molecules bind.
  • Determines the enzyme's specificity for particular substrates.

• Mechanism of Action:

  • Enzymes lower the activation energy required for reactions.
  • Form enzyme-substrate complexes to facilitate reactions.

• Factors Affecting Enzyme Activity:

  • Temperature:
    • Each enzyme has an optimal temperature range.
    • High temperatures can denature enzymes, reducing activity.
  • pH:
    • Each enzyme has an optimal pH level.
    • Deviations can lead to denaturation or reduced activity.
  • Substrate Concentration:
    • Increased substrate concentration generally increases reaction rate until a maximum velocity (Vmax) is reached.
  • Enzyme Concentration:
    • Increasing enzyme concentration typically increases the reaction rate, assuming adequate substrate is available.

• Enzyme Inhibition:

  • Competitive Inhibition: Inhibitor competes with substrate for the active site.
  • Non-competitive Inhibition: Inhibitor binds to an allosteric site, altering enzyme activity without competing for the active site.
  • Uncompetitive Inhibition: Inhibitor binds only to the enzyme-substrate complex, preventing the reaction from proceeding.

• Cofactors and Coenzymes:

  • Cofactors: Inorganic ions (e.g., Mg²⁺, Zn²⁺) that assist enzyme function.
  • Coenzymes: Organic molecules (e.g., vitamins) that act as carriers for chemical groups or electrons.

• Regulation of Enzyme Activity:

  • Allosteric Regulation: Modulators bind to sites other than the active site to enhance or inhibit activity.
  • Feedback Inhibition: End product of a metabolic pathway inhibits an upstream process, maintaining balance.

• Applications:

  • Enzymes are utilized in various industries, including food, pharmaceuticals, and biotechnology (e.g., digestive enzymes, enzyme-linked immunosorbent assay (ELISA)).

Enzymes Overview

• Biological catalysts that expedite chemical reactions in living organisms without undergoing permanent changes themselves.
• Primarily composed of proteins, though some enzymes (ribozymes) consist of RNA, featuring a unique three-dimensional structure essential for their activity.

Active Site and Function

• The active site is the specific region on the enzyme where substrates bind, dictating the enzyme's specificity.
• Enzymes work by lowering the activation energy needed for reactions, facilitating the formation of enzyme-substrate complexes.

Factors Influencing Enzyme Activity

• Temperature: Enzymes have optimal temperature ranges; excessive heat can cause denaturation, which impairs function.
• pH: Each enzyme operates best at a specific pH level, with deviations potentially leading to denaturation or decreased activity.
• Substrate Concentration: Reaction rate typically increases with substrate concentration until the maximum velocity (Vmax) is reached.
• Enzyme Concentration: Increasing enzyme levels generally boosts reaction rates, provided there is enough substrate available.

Enzyme Inhibition Types

• Competitive Inhibition: Inhibitor competes with the substrate for binding at the active site.
• Non-competitive Inhibition: Inhibitor binds to a different site (allosteric site), altering enzyme function without competing for the active site.
• Uncompetitive Inhibition: Inhibitor attaches only to the enzyme-substrate complex, hindering the reaction.

Cofactors and Coenzymes

• Cofactors: Essential inorganic ions (e.g., Mg²⁺, Zn²⁺) that enhance enzyme activity.
• Coenzymes: Organic molecules (e.g., vitamins) that assist by transporting chemical groups or electrons.

Regulation of Enzyme Activity

• Allosteric Regulation: Modulators bind to sites other than the active site, influencing enzyme activity by either enhancing or inhibiting it.
• Feedback Inhibition: The end product of a biochemical pathway negatively regulates an earlier step, ensuring metabolic balance.

Industrial Applications

• Enzymes play crucial roles in various sectors, including food production, pharmaceuticals, and biotechnology. Examples include digestive enzymes and techniques like enzyme-linked immunosorbent assay (ELISA).