Structure of Proteins 3.6

Structure of Proteins 3.6

1. Amino Acids

   • All have the same basic structure
   • Different R groups result in different amino acids
   • 20 are commonly found in cells
   • Catalysed by peptidyl transferase

2. Primary Structure

   • The sequence in which amino acids are joined
   • Determined by DNA
   • Only peptide bonds

3. Secondary Structure

   • The peptide molecule coils or pleats in different sections
   • beta pleated sheets
   • alpha helix
   • Peptide and hydrogen bonds

4. Tertiary Structure

   • The folding of a protein into its final shape
   • Disulphide bridge - only occurs between sulphur atoms and these are the strongest bond
   • Ionic bonds - form between oppositely charged R groups
   • Hydrogen bonds - weakest bonds formed
   • Hydrophobic interactions - between polar and non polar R groups

5. Quarternary structure

   • Only some proteins
   • Defined as this if protein has more than one polypeptide chain or an inorganic compound

6. Thin Layer Chromatography

   • RF = Distance travelled by substance/ Distance travelled by solvent
   • The chemical that travells further will form weaker bonds with the stationary phase. It is also less soluable

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