Encyclopedia of Astrobiology

Living Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James Cleaves, Daniele Pinti, José Cernicharo Quintanilla, Michel Viso


  • Mark DörrEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_1129-2



L-ornithine is a natural, biological, noncoded diamino acid (with α- and δ-amino groups). L-ornithine (Fig. 1) was first isolated by Jaffé from chicken excrement in 1877, hence its name (from Greek: oρνις (ornis) = bird). It plays a major role as a carrier compound in the metabolic urea cycle. Ornithine can be derived from glutamate and is used in the biosynthesis of arginine and is therefore indirectly coupled to protein synthesis in mammals. Polypeptides containing unprotected ornithines undergo spontaneous lactamization. L-ornithine is produced through hydrolysis of citrulline and L-arginine in alkaline medium, that is, the reverse of the biosynthetic process or the same direction observed in the urea cycle. Both L- and D-ornithine have been tentatively identified in the Murchison meteorites (Meierhenrich 2004) (concentration <5 ppb).


Protein Synthesis Molecular Mass Bioorganic Chemistry Alkaline Medium Molecular Formula 
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References and Further Reading

  1. Meierhenrich UJ, Muñoz Caro GM, Bredehöft JH, Jessberger EK, Thiemann WH (2004) Identification of diamino acids in the Murchison meteorite. Proc Natl Acad Sci U S A 101:9182–9186, Available at: http://www.pnas.org/cgi/doi/10.1073/pnas.0403043101 CrossRefADSGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.University of Southern DenmarkOdense MDenmark