either of two pentapeptides that bind to morphine receptors in the central nervous system and have opioid properties of relatively short duration; one pentapeptide (Met enkephalin) has the amino acid sequence Tyr-Gly-Gly-Phe-Met and the other (Leu enkephalin) has the sequence Tyr-Gly-Gly-Phe-Leu.
Origin of enkephalin
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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
Either of two closely related pentapeptides having opiate qualities and occurring especially in the brain and spinal cord.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.