Collagen

• Fibrous protein, insoluble in water, contains 3 polypeptide chains wound around each other, and the third amino acid is glycine (smallest AA); which allows the chains to lie very close to form a tight coil, held together by H bonds
• The shape of a triple left-handed helix structure has quaternary structure but no tertiary structure; these triple helices run parallel to each other and covalent bonds form between the molecule via the lysine R groups
• High tensile strength, resists strong pulling forces (flexible but no stretch); main component of; tendons (connect muscles to bone), artery walls, skin, teeth and bone (over 25 naturally occurring types of collagen in the body)