Hydroxyproline

Hydroxyproline is an amino acid that plays key roles in collagen stability, protein folding, and cellular homeostasis. It is a non-essential amino acid, meaning it can be synthesized by the body.

Biochemistry

Hydroxyproline is produced from proline by the enzyme prolyl hydroxylase following protein synthesis. The hydroxylation reaction consumes oxygen and alpha-ketoglutarate and produces carbon dioxide and succinate as byproducts. This reaction is vitamin C-dependent, and lack of this vitamin can lead to reduced hydroxyproline levels and the disease scurvy.

Function

In collagen, hydroxyproline stabilizes the triple-helix structure by forming hydrogen bonds. It is critical for collagen stability and is overrepresented in collagen compared to other proteins. Hydroxyproline is also involved in cell-signaling pathways related to cellular homeostasis and stress response.

Clinical significance

Abnormal hydroxyproline metabolism can lead to a variety of diseases. For example, overproduction of hydroxyproline has been associated with fibrosis, while underproduction is associated with scurvy and Ehlers-Danlos syndrome. Measurement of hydroxyproline levels can be used as a marker for bone turnover and collagen degradation.

See also

• Amino acid
• Collagen
• Proline
• Prolyl hydroxylase
• Scurvy
• Ehlers-Danlos syndrome
• Fibrosis

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