[ sis-tee-een, -in ]
/ ˈsɪs tiˌin, -ɪn /
a crystalline amino acid, C3H7O2NS, a component of nearly all proteins, obtained by the reduction of cystine. Abbreviation: Cys; Symbol: C
Origin of cysteine
First recorded in 1880–85; alteration of cystine
Related formscys·te·in·ic, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for cysteine
/ (ˈsɪstɪˌiːn, -ɪn) /
a sulphur-containing amino acid, present in proteins, that oxidizes on exposure to air to form cystine. Formula: HSCH 2 CH(NH 2)COOH
Derived Formscysteinic, adjective
Word Origin for cysteine
C19: variant of cystine
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Medicine definitions for cysteine
[ sĭs′tē-ēn′, -ĭn, sĭ-stē′ĭn ]
An alpha-amino acid found in most proteins and especially abundant in keratin.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Science definitions for cysteine
[ sĭs′tə-ēn′ ]
A nonessential amino acid. Chemical formula: C3H7NO2S. See more at amino acid.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.