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cysteine

[sis-tee-een, -in]
noun Biochemistry.
  1. a crystalline amino acid, C3H7O2NS, a component of nearly all proteins, obtained by the reduction of cystine. Abbreviation: Cys; Symbol: C
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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. 2018

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British Dictionary definitions for cysteine

cysteine

noun
  1. a sulphur-containing amino acid, present in proteins, that oxidizes on exposure to air to form cystine. Formula: HSCH 2 CH(NH 2)COOH
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Derived Formscysteinic, adjective

Word Origin

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

cysteine in Medicine

cysteine

(sĭstē-ēn′, -ĭn, sĭ-stēĭn)
n.
  1. An alpha-amino acid found in most proteins and especially abundant in keratin.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

cysteine in Science

cysteine

[sĭstə-ēn′]
  1. A nonessential amino acid. Chemical formula: C3H7NO2S. See more at amino acid.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.