Proteins: Tertiary Structure

Proteins: Tertiary Structure

1. Tertiary Structure – A result of the hydrophobic interactions of amino acids at the core, coupled with the hydrophilic interactions at the surface, coupled with other factors.

2. The overall folding of a protein and therefore also describes its structure in space

3. All the information needed to specify enzyme activity - and therefore tertiary structure - is contained in the amino acid sequence.

4. Hydrophilic exterior made of hydrophilic, acidic and basic AAs

   • Hydration shell surrounds this

5. Surface of protein is affected by pH

   • pH where the net surface charge = 0 is the isoelectric point

6. Hydrophobic core

   • Comprised mostly of 9 hydrophobic AAs
   • All types of secondary structures present
   • Thermodynamics to mantain tertiary structure are finely balanced
     • Entropy associated with dissolution of hydrophobic AAs in water (hydrophobic effect)
     • Van der Waals' forces between hydrophobic chains
     • Other interactions: disulfide bonds and salt bridges
   • Hydrophobic AAs at protein core are brought together because the surrounding water molecules have stronger interactions associated with them than would be seen between hydrophobic AAs and water