from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. An essential amino acid, C4H9CH(NH2)COOH, obtained by the hydrolysis of protein by pancreatic enzymes during digestion and necessary for optimal growth in infants and children and for the maintenance of nitrogen balance in adults.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. An essential amino acid, C6H13NO2, isomeric with isoleucine, found in most animal proteins; it is essential for growth in children.

from the GNU version of the Collaborative International Dictionary of English

  • n. a naturally occurring alpha-amino acid ((CH3)2CH.CH2.CH(NH2)-COOH), one of the building units of almost all proteins of living organisms, both animal and vegetable. It is one of the essential amino acids (not synthesized by the human body, a required component for proper nutrition), and is hydrophobic in character when bound in proteins. In isolated form it is a white, crystalline, zwitterionic substance formed, e. g. by the decomposition of proteins by pancreatic digestion, by the action of boiling dilute mineral acid, or by putrefaction. Chemically it is to be considered as amido-caproic acid. It occurs as two optical isomers, the L- and D-forms. The L-form, L-leucine, is the natural form, present in most proteins.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a white crystalline amino acid occurring in proteins that is essential for nutrition; obtained by the hydrolysis of most dietary proteins


leuc(o)- + -ine2.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Ancient Greek λευκός (leukos, "white") +‎ -ine (Wiktionary)


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  • As a model system for studying real-time protein folding dynamics, the TUM scientists chose a so-called leucine zipper found in yeast. - latest science and technology news stories

  • At the start of the SILK test, volunteers were connected to an intravenous drip that gave them a slightly altered form of the amino acid leucine, which is a component of A-beta.

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  • It was there that they discovered Reuben lacked two amino acids called leucine and isoluceine.

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  • Insulin release is also stimulated by amino acids such as leucine, and insulin stimulates cells to absorb amino acids and to synthesize proteins.

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  • Plant and animal PRRs share conserved domains, such as leucine-rich repeats (LRRs) necessary for PAMP recognition

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  • Thus, we can discern that the genetic code as we understand it today likely evolved in several steps – a stereochemical era wherein a core set of triplet-amino acid correspondences was first established, followed by subsequent expansion of the assignments of other triplets and recruitment of other amino acids (typified by gutamine and leucine) via other mechanisms.

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  • "Recruitment of other amino acids (typified by gutamine and leucine) via other mechanisms" follows.

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  • William Frey II, a biochemist at the St Paul-Ramsey Medical Center in Minneapolis, found that tears aren't just salt water; they contain leucine enkephalin, an endorphin that modulates pain, and hormones such as prolactin and adrenocorticotropic hormone, released at times of stress.

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