Keratin

• Keratin is rich in cysteine so has lots of disulfide bonds between its polypeptide chains.
• Keratin also has hydrogen bonds, making it strong.
• It is found wherever body parts need to be hard and strong - finger nails, hair, claws, hoofs, horns, scales, fur and feathers.
• Keratin provides mechanical protection and an impermeable barrier to infection and, being waterproof, prevents entry of water-borne pollutants.