cystine

American  

[sis-teen, -tin] / ˈsɪs tin, -tɪn /

noun

Biochemistry.

1. 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.

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cystine British  

/ ˈsɪstiːn, -tɪn /

noun

1. a sulphur-containing amino acid present in proteins: yields two molecules of cysteine on reduction. Formula: HOOCCH(NH 2 )CH 2 SSCH 2 CH(NH 2 )COOH

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Etymology

Origin of cystine

1835–45; cyst- + -ine ²; so called because found in the bladder

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Compare meaning

How does cystine compare to similar and commonly confused words? Explore the most common comparisons:

• cysteine vs. cystine

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Example Sentences

See Examples For:

cystine

Nagy's team contributed analytical capabilities that helped the researchers determine how the cells were still obtaining cysteine from cystine despite lacking a working disulfide reductase system.

From Science Daily ● Sep. 25, 2026

The therapy doesn’t have to get into all cells to work, just enough of them to make sufficient amounts of the protein that removes cystine so it doesn’t build up.

From Seattle Times ● Jun. 1, 2021

Specifically, system xc-’s uptake of one molecule of cystine leads to the release of one molecule of glutamate from the cell.

From Scientific American ● Jan. 13, 2020

The trial showed that Procysbi, which was called RP103 during its development, was no worse than Cystagon in controlling the amount of cystine in white blood cells.

From New York Times ● Apr. 30, 2013

On the fifth day she takes a half-teaspoonful of cystine, cysteine, d-1-methionine, l-methionine, cystine-disulfoxide, sulfonic acid or cysteic acid, the seven body sulfur compounds crystallized by Lankenau's Chemist Gerrit Toennies.

From Time Magazine Archive

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