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[sis-teen, -tin] /ˈsɪs tin, -tɪn/
noun, Biochemistry.
a crystalline amino acid, C 6 H 12 O 4 N 2 S 2 , occurring in most proteins, especially the keratins in hair, wool, and horn, and yielding cysteine on reduction.
Origin of cystine
1835-45; cyst- + -ine2; so called because found in the bladder Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for cystine
Historical Examples
  • Ammonia, therefore, dissolves the cystine without entering into chemical union with it.

  • This action is due chiefly to its progressive formation of calcium sulphydrate from the cystine group of the softer keratins.

    Animal Proteins Hugh Garner Bennett
British Dictionary definitions for cystine


/ˈsɪstiːn; -tɪn/
a sulphur-containing amino acid present in proteins: yields two molecules of cysteine on reduction. Formula: HOOCCH(NH2)CH2SSCH2CH(NH2)COOH
Word Origin
C19: see cysto- (bladder), -ine²; named from its being discovered in a type of urinary calculus
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
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cystine in Medicine

cystine cys·tine (sĭs'tēn')
A white crystalline amino acid that is found in many proteins, especially keratin, and is the major source of metabolic sulfur.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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