• Name: trans-4-hydroxyproline
  • Description: An optically active form of 4-hydroxyproline having L-trans-configuration. A nonessential amino acid derivative formed during post-translational protein modification through hydroxylation of the am... ino acid proline by the enzyme prolyl hydroxylase which requires vitamin C as a co-factor. Hydroxyproline is a neutral heterocyclic amino acid. It is the major component of the protein collagen (and as such it is common in many gelatin products) and plays a key role in the stability of the collagen triple helix. Hydroxyproline is mostly used as a diagnostic marker of bone turnover and liver fibrosis. 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. Therapeutically, hydroxyproline is being studied as an experimental medicine but is approved in France as a combination topical gel product called Cicactive for small, superficial wounds. (CHEBI:18095; NCI Thesaurus Code:C76144; DrugBank ID:DB08847)
Overview of age-variations
Age group comparisons
PMID Age/Age interval, Gender Value (unit of measurement) Method Sample
Linear regression
PMID Age/Age interval, Gender Value (unit of measurement) Method Sample
23838602 Age [17–85], Gender ⚥ 0.007 (β) UHPLC/MS/MS serum + plasma
log2 ratio/log2(FC)
PMID Age/Age interval, Gender Value (unit of measurement) Method Sample
  • Synonym:
    L-threo-4-hydroxyproline; (2S,4R)-trans-4-hydroxyproline;trans-4-hydroxy-L-proline
  • Chemical Formula:
  • Exact Mass g/mol:
  • Systematic name:
    (2S,4R)-4-hydroxy-2-pyrrolidinecarboxylic acid; (4R)-4-hydroxy-L-proline
  • InChI:
  • InChI Key:
  • CAS number:
Related resources
Pathway info P = product of S = substrate of
Metabolite sources and localization
  • Metabolite location:
    Human organism, Body part, Human body biofluids, Biofluid tissues, Blood, Blood cells, Platelet, Plasma, Serum, Saliva, Urine, Organ, Kidney, Liver, Muscle, Skeletal muscle, Pancreas, Placenta, Skin, Spleen, Tissue, Connective tissue, Connective tissue cell, Fibroblast, Cellular (general class), Subcellular, Endoplasmic reticulum, Mitochondria, Excreta material, Feces
  • Metabolite source:
    Homo sapiens, endogenous metabolite
Linear regression
Sample: serum + plasma
PubMed PMID: 23838602
β = 0.007 (y = βx + α)
p-value < 0.05