Amino Acids have acid and base properities
- General formular
- 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
- High melting points as they are ionic
Proteins and formation of peptide links
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).
Hydrolysis of peptide links produce original amino
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
Hydrogen bonding in proteins
Complex structures in proteins held together by hydrogen bonding
Shapes of proteins vital to function (e.g. enzymes and active site!)