fibrous proteins

• What is a key property of fibrous proteins?

  They are insoluble and unreactive molecules

  
• Why are fibrous proteins insoluble?

  Due to high proportion of hydrophobic R-groups
• What is a specific fibrous protein found in hair, skin, and nails?

  Keratin

  
• What is the amino acid sequence characteristic of fibrous proteins?

  It is usually repetitive
• What type of structure do fibrous proteins typically have?

  Long, unfolded structures with little tertiary structure
• What amino acid is abundant in keratin?

  Cysteine
• How do disulphide bridges affect keratin's properties?

  They make keratin strong and inflexible
• Where is collagen found in the body?

  Skin, ligaments, tendons, and bones
• What is the overall function of collagen?

  It holds tissues together structurally
• What gives collagen its tensile strength?

  Small range of amino acids and polypeptide chains
• What type of bonding is present in collagen?

  Hydrogen bonds and cross-linking covalent bonds
• What is the primary structure of collagen?

  Three polypeptide chains tightly wound
• What is the secondary structure of collagen?

  It has little tertiary structure
• What is the overall property of elastin?

  It provides strength and flexibility

  
• Where is elastin found in the body?

  In blood vessels and alveoli in lungs
• What is the primary sequence characteristic of elastin?

  Alternate hydrophobic and lysine-rich areas
• What happens to tropoelastin molecules in elastin?

  They aggregate to form large, insoluble elastin
• How is the stability of elastin achieved?

  Through cross-linking covalent bonds between lysine
• What are the structures specific to collagen that help its function?

  • Primary: Three polypeptide chains
  • Secondary: Little tertiary structure
  • Tertiary: Minimal folding
  • Quaternary: Strong, rope-like structure
• What are the structures specific to elastin that help its function?

  • Primary: Alternate hydrophobic and lysine-rich areas
  • Secondary: Soluble tropoelastin molecules
  • Tertiary: Stretchable and recoiling structure
  • Quaternary: Large, insoluble elastin with cross-linking