Pathway of ornithine synthesis - Proline, ornithine and arginine metabolism - HORT640 - Metabolic Plant Physiology - Department of Horticulture and Landscape Architecture - Purdue University

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N Use By Plants

Nitrate Assimilation

Ammonia Assimilation

Glu, Gln, Asn, Gly, Ser

Aminotransferases

Val, Leu, Ileu, Thr, Lys

Non-protein AAs

Sulfate Assimilation

Cys, Met, AdoMet, ACC

His, Phe, Tyr, Tryp

Secondary Products

Onium Compounds

HORT640 - Metabolic Plant Physiology
Proline, ornithine and arginine metabolism

Pathway of ornithine synthesis

From: Thompson (1980)

1. Acetyl-CoA: L-glutamate N-acetyltransferase (amino-acid N-acetyltransferase)

Acetyl-CoA + glutamate ---> N-acetylglutamate + CoA

2. N²-Acetyl-L-ornithine: L-glutamate N-acetyltransferase (glutamate N-acetyltransferase)

N²-Acetyl-L-ornithine + glutamate ---> ornithine + N-acetylglutamate

3. ATP: N-Acetyl-L-glutamate 5-phosphotransferase (N-acetyl-L-glutamate kinase)

ATP + N-acetylglutamate --(Mg²⁺)--> N-acetylglutamyl 5-phosphate + ADP

4. N-Acetyl-L-glutamate-5-semialdehyde: NADP⁺ oxidoreductase [phosphorylating] (N-acetyl-L-glutamate semialdehyde dehydrogenase)

N-Acetylglutamyl 5-phosphate + NAD(P)H + H⁺ <---> N-acetylglutamyl-5-semialdehyde + NAD(P)⁺ + Pi

5. N²-Acetyl-L-ornithine: 2-oxoglutarate aminotransferase

Glutamate + N-acetylglutamyl-5-semialdehyde --(Pyr-P)--> 2-oxoglutarate + N²-acetylornithine

6. N²-Acetyl-L-ornithine deacetylase

N²-Acetyl-L-ornithine + H₂O ---> ornithine + acetic acid

References

Thompson JF 1980 Arginine synthesis, proline synthesis, and related processes. In "The Biochemistry of Plants", Vol 5 (BJ Miflin ed) Academic Press, New York, pp. 375-403.

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David Rhodes Department of Horticulture & Landscape Architecture Horticulture Building 625 Agriculture Mall Drive Purdue University West Lafayette, IN 47907-2010 Last Update: 03/31/08