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)