A hydroxylated form of the imino acid proline. A deficiency in ASCORBIC ACID can result in impaired hydroxyproline formation.

A nonessential amino acid derivative formed during post-translational protein modification through hydroxylation of the amino acid proline by the enzyme prolyl hydroxylase which requires vitamin C as a co-factor. Hydroxyproline is a major component of the protein collagen and plays a key role in the stability of the collagen triple helix. It can be used as an indicator to determine the amount of collagen. Increased hydroxyproline levels in the urine and/or serum are normally associated with degradation of connective tissue. Vitamin C deficiency decreases the conversion of proline to hydroxyproline, which leads to reduced collagen stability.

C5H9NO3; amino acid derived from proline, found in collagen and gelatin.

As a major part of collagen, hydroxyproline has an essential role in collagen stability. Testing hydroxyproline in the serum and in the urine is common.