Introduction to Proteins and Enzymes

Proteins

• Definition: Large, complex molecules made up of amino acids.

• Structure:

  • Primary: Sequence of amino acids.
  • Secondary: Folding into alpha-helices and beta-pleated sheets.
  • Tertiary: 3D structure formed by further folding and interactions.
  • Quaternary: Assembly of multiple polypeptide chains.

• Functions:

  • Catalysis (enzymes)
  • Structural support
  • Transport and storage (e.g., hemoglobin)
  • Signaling (hormones)
  • Immune response (antibodies)

• Amino Acids:

  • 20 standard amino acids.
  • Classified as essential (must be obtained from diet) or non-essential (can be synthesized).

• Peptide Bonds: Link amino acids in proteins through condensation reactions.

Enzymes

• Definition: Biological catalysts that speed up chemical reactions in living organisms.

• Characteristics:

  • Highly specific to substrates.
  • Lower activation energy for reactions.
  • Not consumed in reactions; can be reused.

• Mechanism:

  • Active Site: Region where substrate binds.
  • Enzyme-Substrate Complex: Temporary structure formed during the reaction.

• Factors Affecting Enzyme Activity:

  • Temperature: Optimal temperature usually increases activity; high temperatures can denature enzymes.
  • pH: Each enzyme has an optimal pH; deviations can reduce activity.
  • Substrate Concentration: Increasing substrate concentration boosts reaction rate until saturation point is reached.

• Enzyme Inhibition:

  • Competitive Inhibition: Inhibitor competes with substrate for active site.
  • Non-competitive Inhibition: Inhibitor binds elsewhere, altering enzyme function.

• Cofactors and Coenzymes:

  • Cofactors: Inorganic ions (e.g., Mg²⁺, Zn²⁺) necessary for activity.
  • Coenzymes: Organic molecules (e.g., vitamins) that assist in enzyme function.

Importance

• Proteins play crucial roles in virtually all biological processes.
• Enzymes are critical for metabolic pathways and cellular functions.

Proteins

• Large molecules composed of amino acids linked by peptide bonds
• Four levels of structure:
  • Primary Structure: Linear sequence of amino acids
  • Secondary Structure: Folding into alpha-helices or beta-pleated sheets
  • Tertiary Structure: Three-dimensional structure formed by further folding and interactions between amino acids
  • Quaternary Structure: Assembly of multiple polypeptide chains
• Perform a wide range of functions including:
  • Catalysis: Enzymes facilitate chemical reactions
  • Structural Support: Provide shape and stability for cells and tissues
  • Transport and Storage: Molecules like hemoglobin carry and store substances (e.g., gases)
  • Signaling: Hormones act as messengers for communication between cells
  • Immune Response: Antibodies defend against pathogens

Amino Acids

• 20 standard amino acids are used to build proteins
• Essential amino acids must be obtained from the diet, while non-essential amino acids can be synthesized by the body

Enzymes

• Biological catalysts that speed up chemical reactions in living organisms
• Highly specific to their substrates, meaning they act only on specific molecules
• Reduce the activation energy required for reactions
• Do not participate in the reaction and can be reused
• Key features include:
  • Active Site: Region on the enzyme where the substrate binds
  • Enzyme-Substrate Complex: Transient structure formed during the reaction
• Factors affecting enzyme activity:
  • Temperature: Optimal temperature is often a specific range, while extreme temperatures can denature enzymes
  • pH: Each enzyme has an optimal pH, and deviation from this range can reduce activity
  • Substrate Concentration: Increasing substrate concentration generally increases reaction rate until a saturation point is reached
  • Enzyme Inhibition:
    • Competitive Inhibition: Inhibitor molecule competes with the substrate for the active site
    • Non-competitive Inhibition: Inhibitor binds to a different site on the enzyme, changing its shape and reducing its activity
• Cofactors and Coenzymes:
  • Cofactors: Inorganic ions (e.g., Mg²⁺, Zn²⁺) that are often necessary for enzyme activity
  • Coenzymes: Organic molecules (e.g., vitamins) that assist in enzyme function

Importance

• Proteins are essential for nearly all biological processes
• Enzymes are crucial for metabolic pathways, allowing cells to function efficiently

Explore the essential characteristics and functions of proteins and enzymes. This quiz covers protein structure, the role of amino acids, and the significance of enzymes as biological catalysts. Test your knowledge on how these molecules contribute to various biological processes.