different types of proteins

• globular protein?


  contain pp chains joined by peptide bonds, folded into compact spherical shape.

  • tertiary structure, held by ionic, disulphide of hydrogen bonds, specific functional 3d shape
  • many hydrophilic R groups on outside of protein.

  soluble in water due to philic side chains and can be seen as important in metabolic reactions:

  • eg enzymes, some hormones, channel proteins ect
• fibrous protein?

  contain long linear pp chains with repetitive sequence of AA

  • little/no tertiary structure so mostly secondary (helix/pleated)
  • many pp chains lie parallel to each other with cross links
  • hydrophobic R groups on outside of protein.

  insoluble in water due to phobic groups, important for structure:

  • keratin, collagen, fibrin
• conjugated protein?

  have another chemical group (prosthetic) associated with pp chains, examples:

  • haemoglobin= associated with iron- containing group
  • glycoproteins= prosthetic made of carbohydrates
  • lipoproteins= proteins + lipids
• compare structure/functions of globular and fibrous proteins?

  • both composed of AA held by polypeptide bonds
  • both have secondary/more complex structures (made of 1+ pp)
  • pp in G are highly folded to be compact, F remain straight
  • G is soluble, F is insoluble
  • G isn't very stable, F is stable/strong
  • G is important for molecular interactions (enzymes), F is important for structure