Encyclopedia of Astrobiology

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


  • Kensei Kobayashi
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_1282-4



Proline, C 5H 9NO 2, is one of the 20 protein amino acids. The amine in proline is a secondary amine (Fig. 1), whereas the other 19 coded amino acids all contain primary (−NH 2) amino groups. Its three-letter symbol is Pro, and its one-letter symbol is P. It has a molecular weight of 115.13, and its isoelectric point is 6.30. Proline is a hydrophobic amino acid. Since it contains a secondary amino group, its reactivity is different from that of the other amino acids, and special care is needed for its determination. For example, the reaction product of proline with ninhydrin is of a different color from that of the other coded amino acids.


Molecular Weight Bioorganic Chemistry Isoelectric Point Special Care Secondary Amine 
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© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Yokohama National UniversityYokohamaJapan