Hydroxyproline is a neutral heterocyclic protein amino acid. It is found in collagen and as such it is common in many gelatin products. Hydroxyproline is mostly used as a diagnostic marker of bone turnover and liver fibrosis.

What is the main source of hydroxyproline in the body?

Hypro is derived from dietary collagen and endogenously from the turnover of muscle, connective tissue, and bone. Most Hypro is catabolized in the epithelial cells of renal proximal tubules, smaller amounts in the liver.

Where does hydroxylation occur in the body?

Collagen, an essential part of connective tissue, forms 25%–35% of the proteins in our bodies. The hydroxylation occurs at the γ-Carbon atom of Proline, forming hydroxyproline (Hyp), which is an essential component of collagen occurring at every 3rd residue in its amino acid sequence.