structure

• AA -> protein?

  • 2 amino acids join in condensation reaction (between amino group and carboxyl group)
  • molecule of water is lost, peptide bond is formed
  • becomes polypeptide when many AA joined
  • becomes protein when pp chains fold with other pp chains
• primary structure?

  sequence of amino acids that make up a polypeptide chain.

  it determines:

  • order of amino acid R groups
  • which bonds form between R groups (determines what specific foldings take place)
• secondary structure?

  hydrogen bonds form between negative C=O and positive N-H

  • may twist to form an alpha helix (spring)
  • several pp chains may link together with hydrogen bonds holding parallel chains in a beta pleated sheet
• tertiary structure?

  folding of secondary structure into precise 3d shape.

  chemical bonds (hydrogen, disulphide, ionic) maintain the structure.

  • polar R groups attract other polar molecules, non polar R groups repel water (centre of protein)
• bonds in proteins?

  • hydrogen= form between pos O of carboxyl and neg H of amino, important in folding/coiling chains
  • disulphide= form between R groups containing -SH groups, stronger than hydrogen bonds
  • ionic= form between ionised R groups (strong pos/neg)
• what is important to know about the hydrogen bonds in protein structure?

  bonds are involved in both secondary and tertiary, but form different groups:

  • secondary, between H atom of NH in peptide bond and O atom of CO from another peptide bond
  • tertiary, form between atom in R group of one AA and atom of R group in another AA (normally H and O)

  atoms are always delta !
• quaternary structure?

  3d arrangement of more than one tertiary polypeptide