So what is the structure of Collagen? Well, Collagen has a coronary structure, and one of the most abundant amino acids in Collagen is proline. Now, what Collagen does is it modifies the structure of proline by adding a hydroxyl group to produce hydroxyproline. And what that does is it increases the stability of the three dimensional structure of Collagen. So Collagen, the most abundant protein in our body, contains proline amino acids that contain hydroxyl groups. These hydroxyl groups, as shown in the following diagram, basically give the Collagen its stability.