# Endorphin - "only five amino acids" any way to make that statement true? **URL:** \ **Category:** Factual Questions\ **Created:** [May 6, 2013, 8:34am UTC](https://boards.straightdope.com/t/endorphin-only-five-amino-acids-any-way-to-make-that-statement-true/657603 "2013-05-06T08:34:51Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [May 6, 2013, 8:34am UTC](https://boards.straightdope.com/t/endorphin-only-five-amino-acids-any-way-to-make-that-statement-true/657603/1 "2013-05-06T08:34:51Z")
As a practical excercise in teaching 16-year-olds the mechanics of protein synthesis I use a cut and paste and move components around task copied from someones copy of a copy of an unknown book. The intro text on the excercise sheet says “Endorphin … consist of just five amino acids in this order: Tyr-Gly-Gly-Phe-Met” After using it for a few years I figured it’d be fun to show the structure of the actual molecule, and I was wondering how over-simplified the explanation was since it didn’t match my growing understanding of protein synthesis and I discover that beta and alfa endorphin may _start_ with Tyr-Gly-Gly-Phe-Met but are actually much longer chains and also the result (as I suspected) of an even larger precursor being synthesised and then chopped into pieces. So I’m wondering, is the sentence “Endorphin … consist of just five amino acids in this order: Tyr-Gly-Gly-Phe-Met” just a complete lie from the creator of the exercise, or could a biochemist find a way to justify it as a lie-to-children simplification? ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [May 6, 2013, 8:54am UTC](https://boards.straightdope.com/t/endorphin-only-five-amino-acids-any-way-to-make-that-statement-true/657603/2 "2013-05-06T08:54:21Z")
> [@naita](#): > > As a practical excercise in teaching 16-year-olds the mechanics of protein synthesis I use a cut and paste and move components around task copied from someones copy of a copy of an unknown book. > > The intro text on the excercise sheet says “Endorphin … consist of just five amino acids in this order: Tyr-Gly-Gly-Phe-Met” How can one give one formula for EVERY endorphin.. there are lots of endorphins. That formulai s for Met-enkephalin Met-enkephalin, sometimes referred to as opioid growth factor is a naturally occurring, endogenous opioid peptide that has opioid effects of a relatively short duration. It is one of the two forms of enkephalin, the other being leu-enkephalin. The enkephalins are considered to be the primary endogenous ligands of the δ-opioid receptor, due to their high potency and selectivity for the site over the other endogenous opioids. ---
**Author:** ![grude](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@grude](https://boards.straightdope.com/u/grude)\ **Post date:** [May 6, 2013, 9:05am UTC](https://boards.straightdope.com/t/endorphin-only-five-amino-acids-any-way-to-make-that-statement-true/657603/3 "2013-05-06T09:05:45Z")
Isilder is probably way more qualified, but would saying the body makes or synthesizes endorphins from be a better phrasing? ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [May 6, 2013, 1:33pm UTC](https://boards.straightdope.com/t/endorphin-only-five-amino-acids-any-way-to-make-that-statement-true/657603/4 "2013-05-06T13:33:25Z")
So my Norwegian online medical dictionary has enkephalins as a subgroup of endorphins, while Wikipedia has endorphins and enkephalins as separate subgroups of opioid peptides. Does this reflect changes in how the terms are used, or differences between countries? ---
**Author:** ![ArmenE](https://avatars.discourse-cdn.com/v4/letter/a/e9bcb4/32.png) [@ArmenE](https://boards.straightdope.com/u/ArmenE)\ **Post date:** [May 6, 2013, 3:09pm UTC](https://boards.straightdope.com/t/endorphin-only-five-amino-acids-any-way-to-make-that-statement-true/657603/5 "2013-05-06T15:09:45Z")
I’m a biologist and see no problem with the statement. ---
**Author:** ![Anaglyph](https://avatars.discourse-cdn.com/v4/letter/a/ed8c4c/32.png) [@Anaglyph](https://boards.straightdope.com/u/Anaglyph)\ **Post date:** [May 6, 2013, 3:19pm UTC](https://boards.straightdope.com/t/endorphin-only-five-amino-acids-any-way-to-make-that-statement-true/657603/6 "2013-05-06T15:19:43Z")
Both human [pro-enkephalin A](http://www.uniprot.org/uniprot/P01210) and [pro-enkephalin B](http://www.uniprot.org/uniprot/P01213) are produced as large proteins (\>250 amino acids). They start with a 20 AA pre-sequences required for secretion and get cleaved by protease to each yield several different biologially active peptides. ---
**Author:** ![Anaglyph](https://avatars.discourse-cdn.com/v4/letter/a/ed8c4c/32.png) [@Anaglyph](https://boards.straightdope.com/u/Anaglyph)\ **Post date:** [May 6, 2013, 3:26pm UTC](https://boards.straightdope.com/t/endorphin-only-five-amino-acids-any-way-to-make-that-statement-true/657603/7 "2013-05-06T15:26:16Z")
Endorphin is a functional description for endogenous peptides that bind to the opoid receptors. Met-enkephalin and Leu-enkephalin are 5-amino acid peptide fragments of the two enkephalin precursor protein that happen to show endorphin activity. ---
**Author:** ![deltasigma](https://avatars.discourse-cdn.com/v4/letter/d/e5b9ba/32.png) [@deltasigma](https://boards.straightdope.com/u/deltasigma)\ **Post date:** [May 7, 2013, 3:19pm UTC](https://boards.straightdope.com/t/endorphin-only-five-amino-acids-any-way-to-make-that-statement-true/657603/8 "2013-05-07T15:19:01Z")
I found this under the [wiki enkephalin entry](http://en.wikipedia.org/wiki/Enkephalin#Endogenous_opioid_peptides) and it seems to indicate some overlap - note the bolded part. > [@](#): > > There are three well-characterized families of [opioid peptides produced by the body](http://en.wikipedia.org/wiki/Opioid_peptide#Opioid_peptides_produced_by_the_body): enkephalins, [endorphins](http://en.wikipedia.org/wiki/Endorphins), and [dynorphins](http://en.wikipedia.org/wiki/Dynorphins). The met-enkephalin peptide sequence is coded for by the enkephalin gene; **the leu-enkephalin peptide sequence is coded for by both the enkephalin gene and the dynorphin gene**.[[3]](http://en.wikipedia.org/wiki/Enkephalin#cite_note-3) The proopiomelanocortin gene ([POMC](http://en.wikipedia.org/wiki/POMC)) also contains the met-enkephalin sequence on the N-terminus of beta-endorphin, but the endorphin peptide is not processed into enkephalin.