Encyclopedia of Astrobiology

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

Cystine

Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_383-4

Definition

Cystine (Fig. 1) is formed by the oxidative condensation of two cysteine molecules. Cysteine, one of the 20 protein amino acids, has a thiol (─SH) group. In aqueous solution, two thiol groups readily oxidize to form a disulfide bond (─S─S─). Thus, cystine rather than cysteine is usually determined when the amino acid composition of protein hydrolysates is analyzed. It can be easily reduced to give two cysteine molecules. In protein molecules, cysteine residues make intramolecular disulfide bonds, which stabilize protein tertiary structure.

Keywords

Aqueous Solution Acid Composition Bioorganic Chemistry Disulfide Bond Cysteine Residue 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
This is a preview of subscription content, log in to check access

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Yokohama National UniversityYokohamaJapan