Amino acid

• General formular
  • H2NCHRCOOH
    • other than glycerine all amino acids are chiral
• Carboxylic group has a tendency to lose a proton
  • -COOH --(eqm)--> -COO- + H+
• amine group has tendency to accept a proton in strongly acidic conditions
  • H+ + -NH2 --(eqm) --> -NH3+
• Amino acids can exist and Zwitterion
  • H3NHCRCOO
  • High melting points as they are ionic

Proteins are sequences of amino acids joined by peptide links

• H2NHCRCOOK + H2NRCHCOOH --> H2NCONHRCHCOOH + H2O
  • the two amino acids are linked by a peptide bond.
  • can react again to form large peptide chains
  • The above reaction is a condensation reaction (H2O eliminated).

when a protein or peptide is boiled with HCl acid of conc 6 mol dm-3 for about 24 hours it breaks down to a mixture of amino acids.

Acid hydrolises the peptide links

• H2NRCHCONHRCHCOOH +H2O --(H+ catalyst)--> 2H2NRCHCOOH

These amino acid mixtures can be separated by chromatography.

• allows us to find out which ones are present

Complex structures in proteins held together by hydrogen bonding

Shapes of proteins vital to function (e.g. enzymes and active site!)