iso·​leu·​cine ˌī-sō-ˈlü-ˌsēn How to pronounce isoleucine (audio)
: a crystalline, hydrophobic, essential amino acid C6H13NO2 that is obtained in its levorotatory l-form by the hydrolysis of dietary protein and is isomeric with leucine

Examples of isoleucine in a Sentence

Recent Examples on the Web Challenging workouts and proper fueling will be your best muscle builders. BCAAs BCAAs contain three essential amino acids: leucine, isoleucine, and valine. Donavyn Coffey, TIME, 1 Apr. 2024 High-quality protein is any protein that contains all of the nine essential amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine) that our bodies don’t make on their own. USA TODAY, 2 July 2023 Leucine, isoleucine, and valine are the three BCAAs. Amber Smith, Discover Magazine, 16 Nov. 2022 Some important plant proteins, like asparagus and lily, have low levels of isoleucine and lysine. Amber Smith, Discover Magazine, 16 Dec. 2022 Every scoop of Plant JYM Vegan Protein Powder contains 24 grams of protein and five grams of leucine, isoleucine and valine, stacked at the recommend 2:1:1 ratio. Dallas News, 15 Feb. 2022

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'isoleucine.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


International Scientific Vocabulary

First Known Use

1903, in the meaning defined above

Time Traveler
The first known use of isoleucine was in 1903

Dictionary Entries Near isoleucine

Cite this Entry

“Isoleucine.” Dictionary, Merriam-Webster, Accessed 30 May. 2024.

Medical Definition


iso·​leu·​cine ˌī-sō-ˈlü-ˌsēn How to pronounce isoleucine (audio)
: a crystalline essential amino acid C6H13NO2 isomeric with leucine
abbreviation Ile

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