Pyrroline-5-carboxylate reductase

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pyrroline-5-carboxylate reductase
Pyrroline-5-carboxylate reductase 1 dekamer, Human
EC no.
CAS no.9029-17-8
IntEnzIntEnz view
ExPASyNiceZyme view
MetaCycmetabolic pathway
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO

In enzymology, a pyrroline-5-carboxylate reductase (EC is an enzyme that catalyzes the chemical reaction

L-proline + NAD(P)+ 1-pyrroline-5-carboxylate + NAD(P)H + H+

The 3 substrates of this enzyme are L-proline, NAD+, and NADP+, whereas its 4 products are 1-pyrroline-5-carboxylate, NADH, NADPH, and H+.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-proline:NAD(P)+ 5-oxidoreductase. Other names in common use include proline oxidase, L-proline oxidase, 1-pyrroline-5-carboxylate reductase, NADPH-L-Delta1-pyrroline carboxylic acid reductase, and L-proline-NAD(P)+ 5-oxidoreductase. This enzyme participates in arginine and proline metabolism.

Structural studies[edit]

As of late 2007, 5 structures have been solved for this class of enzymes, with PDB accession codes 2AHR, 2GER, 2GR9, 2GRA, and 2IZZ.

Human genes[edit]

  • PYCR1, nuclear gene for mitochondrial protein
  • PYCR2, nuclear gene for mitochondrial protein
  • PYCR3 (formerly PYCRL), cytosolic protein


  • Adams E; Goldstone A (1960). "Hydroxyproline metabolism. III. Enzymatic synthesis of hydroxyproline from Delta1-pyrroline-3-hydroxy-5-carboxylate". The Journal of Biological Chemistry. 235 (12): 3499–3503. doi:10.1016/S0021-9258(18)64497-7. PMID 13681369.
  • Meister A, Radhakrishnan AN, Buckley SD (1957). "Enzymatic synthesis of L-pipecolic acid and L-proline". The Journal of Biological Chemistry. 229 (2): 789–800. doi:10.1016/S0021-9258(19)63684-7. PMID 13502341.
  • Smith ME; Greenberg DM (1956). "Characterization of an enzyme reducing pyrroline-5-carboxylate to proline". Nature. 177 (4520): 1130. Bibcode:1956Natur.177.1130S. doi:10.1038/1771130a0. PMID 13334497. S2CID 4298013.
  • Yura T; Vogel HJ (1959). "Pyrroline-5-carboxylate reductase of Neurospora crassa: partial purification and some properties". The Journal of Biological Chemistry. 234 (2): 335–338. doi:10.1016/S0021-9258(18)70299-8. PMID 13630905.