Talk:Peptide

Peptides vs. Proteins:

Q: What is the difference between a peptide and a protein? :S Brutulf 16:34, Apr 4, 2005 (UTC)

A: Peptides are less than 50 amino acids long and they do not have secondary and tertiary structures. Therefore they can fold into a variety of shapes. e.g. Insulin. Proteins, however, have more than 50 amino acids. They have secondary and tertiary structures, and therefore most proteins have fixed shapes. e.g. Hemoglobin.

• See Also: Grand Peptide List The Biochemical Basis of Neuropharmacology Oxford Press 1996--McDogm 16:42, 6 May 2005 (UTC)

Q: I disagree - my teacher says that peptides are simply chains of proteins.

A: Peptides and proteins are both chains of amino acids. However proteins are longer chains. This is probably what your teacher was referring to. Archie 11:46, 8 April 2006 (UTC)

Q: I'm doing a PhD thesis on membrane-peptide interactions. I believe the following is not true (cited from wikipedia article): Because of the arbitrary nature of this definition, there is considerable movement within the scientific community to ascribe the more-specific definition that "a peptide is an amino acid molecule without secondary structure; on gaining defined structure, it is a protein." Suggestion: delete it.

A: I'm a pharmaceutical recruiter. I have placed many candidates in peptide positions. Many chemist that I speak with consider protiens and peptides to be one in the same unless you speak with someone who's focus is in peptides. They indicate that there is a huge difference between the two. If you are looking at peptides strictly in the chemical sence they are both protiens, but peptides are a subgroup and avid peptide chemist will not agree that peptides and protiens should be lumped together and considered similar. —Preceding unsigned comment added by 70.90.89.145 (talk) 12:51, 7 April 2009 (UTC)

Re: "are less than 50 amino acids long and they do not have secondary and tertiary structures. Therefore they can fold into a variety of shapes. e.g. Insulin." - I'm afraid I have to disagree with that! Insulin most definitely has a well defined secondary and tertiary structure! I(q) = User(q)·Talk(q) 15:08, 3 September 2011 (UTC)

Nevertheless there a huge differences even between proteins. And without any doubt complex "peptides" like insulin are in fact proteins, they just wear the wrong name. IMHO all peptides with secondary and tertiary structures are proteins. "It' the structure, s.....". --178.197.229.5 (talk) 00:40, 17 January 2014 (UTC)

I don't think we should have to come to the talk page to find out if proteins qualify as peptides. There should be at least a sentence in the article making clear that chains of over approximately 50 residues aren't allowed to call themselves peptides. 2602:306:BC65:4069:1511:E4C9:2E9E:4950 (talk) 20:37, 5 June 2022 (UTC)

External Peptide Links

• Peptide Information, bioinformatics, protocols, and lists of services. Bioinformin

This section needs references

I can't find any reliable references about dermorphin, casomorphin or gluten exorphin contributing to mental illness in PubMed. Tim Vickers 03:21, 17 October 2007 (UTC)

Digested peptides

Are the result of nonspecific proteolysis as part of the digestive cycle. It has also been documented that, when certain food proteins such as gluten, casein, egg protein, and spinach protein are broken down, opioid peptides are formed. These peptides mimic the effects of morphine, and those individuals that are unable to break them down will experience mental illness. These peptides are quite short and are given names such as casomorphin, gluten exorphin, and dermorphin. Ultimately digested peptides are ribosomal peptides, although they aren't made on the ribosome of the organism that contains them.

Isobaric peptides

"Isobaric peptides" rederects here, but there isn't any information on that page, not even the word itself... I'm currently finishing my thesis, but if someone has the time... Kosmologie (talk) 14:30, 15 September 2009 (UTC)

"small digestibles" / πεπτίδια

Any chance someone whose Greek is a bit sounder than mine could check the translation (in the introduction)

       Greek πεπτίδια, "small digestibles"

? I don't think the 'small' idea appears within the meaning of πεπτίδια. That is, I think πεπτίδια means "digestibles" rather than "small digestibles". I'm not even sure about "digestibles" (I think it may mean "things that have been digested": "digestion products"), but it's 'small' that matters - because of the confusion / controversy about peptides / polypeptides / proteins. Some people (see posts above) consider that the size of the molecule is the point here (eg 50+ is a polypeptide or protein), some the structure (ie secondary/tertiary means protein, primary-only means peptide) - and of course the other 99+% of readers aren't specialists, have no opinion and are hoping it's our role to inform them.

Of this non-specialist majority, many are 'victims' turning to us for rescue from drowning in 'cosmeceutical' guff.

On the specialist side of the fence, I gather small polypeptides like cytokines are an emerging and increasingly autonomous area of study. (There's an interesting long post on the talk-page for Cytokines, about a claimed almost regulatory role in the mind/body relationship under conditions of immune-challenge. It argues that the fairly new-drafted article is behind the times.) Within this new field, I suspect some partisans view typically larger molecules like hormones as unfashionable subjects ("so last-century, dahling"?). (Where passions run high, NPOV Wikipronouncements will have special value.)

I'm kinda guessing, though, about this. Can anyone with direct experience of the research community/ies comment? edit boldly?

As a simple opening move, can someone more confident of their Greek sharpen up the πεπτίδια thing?

SquisherDa (talk) 06:59, 25 June 2010 (UTC)

Figures

Isn't it a bit overkill to have figures of *two* dipeptides *and* one tetrapeptide? The figure of the tetrapeptide should be sufficient. Carstensen (talk) 11:37, 20 October 2011 (UTC)

I'd agree, it also doesn't help that the Gly-Ala dipeptide image is looking a bit dated. (+)H₃N-Protein\Chemist-CO₂(-) 14:15, 21 October 2011 (UTC)

What about copper peptides?

In the article about peptides, there is nothing about it. http://en.wikipedia.org/wiki/Copper_peptide_GHK-Cu Why? — Preceding unsigned comment added by Kenorb (talk • contribs) 09:43, 13 February 2012 (UTC)

Peptides and their (illegal?) use in sports.

Peptides are in the news this week in Australia in relation to some kind of illegal use in sports. Does someone with any knowledge of those stories, and/or the possible benefits of peptides want to add a new section to the article? I cam here to find out why they might be useful or banned but didn't see anything relevant. — Preceding unsigned comment added by 124.149.169.161 (talk) 11:18, 11 February 2013 (UTC)

Beauty products?

Every advert at the moment claims that pentapeptides can make their produce "reduce the signs of aging"... I came to this article to find out if this was true, but no luck. Possibly a section needed to address this as this term has become a household term recently. —Preceding unsigned comment added by Giant toaster (talk • contribs) 07:44, 29 June 2008 (UTC)

Doesn't seem either probable or important to me. Tim Vickers (talk) 15:50, 29 June 2008 (UTC)

Attributing some property to a peptide on the grounds that it is a pentapeptide (ie, consists of 5 amino acids) is like saying a molecule with 5 carbon atoms will have a specific property; ie nonsensical. —Preceding unsigned comment added by 121.79.24.62 (talk) 02:42, 8 August 2008 (UTC)

This is true, but the fact is that Olay - at least in the UK - is making such claims relating to pentapeptides. As Giant Toaster says, the term has become far more widely known as a result. Nick Cooper (talk) 07:51, 16 August 2008 (UTC)

We're getting an increasingly annoying commercial in Britain starting with an American fashion advisor saying "have you heard about pentapeptides?". Is there any scientific data on pentapeptides of some sort being effective in moisturisor? I doubt it, but it would be nice to hear from an expert.

• See http://www.pgdermatology.com/downloads/documents/Pentapeptide-Brochure-FINAL-090805.pdf (6 pages, 600 kB) which is by Proctor and Gamble (makers of Olay), and refers to a particular pentapeptide, palmitoyl KTTKS (lysine-threonine-threonine-lysine-serine) or pal-KTTKS. As the authors of the brochure have a commercial interest, this would need more investigation before documenting in an encyclopedia. As it is one of millions of peptides in nature, in my opinion description of it doesn't belong in the Peptide article. Hope that helps. --Hroðulf (or Hrothulf) (Talk) 13:34, 11 December 2010 (UTC)

There was a new section added a few hours ago "peptides in cosmetics", whose final paragraph heavily promotes one company like this: ".... cosmetic active ingredients with diverse benefits. The most renowned are those from the Matrixyl™ range." This makes me concerned about the balance of the entire section, which was contributed by one editor.diff Although the rest seems to be sourced, is it objective and balanced and was it written by a paid advocate? --Hroðulf (or Hrothulf) (Talk) 14:33, 24 January 2014 (UTC)

The new section seems skechy. I removed the obvious advertising, but the whole section should be removed in my opinion. CombatWombat42 (talk) 18:30, 24 January 2014 (UTC)

I understand your point about the last paragraph and it is true that it concerns only one peptide among millions of them, so it should be removed. But I don't understand why you removed the whole section, it is properly documented (valid scientific reference) and as you mentioned at the beginning of this section, peptides are more and more mentioned in the cosmetic industry and it is important to explain in an article dealing with peptides why and how they are used for these specific applications. The researches made for medical applications are often used in cosmetics as the skin is a major organ of the human body.Pcriton (talk) 12:45, 28 January 2014 (UTC)pcriton

I have moved the material by Pcriton (talk · contribs) to a draft where you can work on it further (with assistance from other Wikipedians): Draft:Peptides in skin care. --Hroðulf (or Hrothulf) (Talk) 13:54, 28 January 2014 (UTC)

Thanks for the move, Hroðulf. My concerns about the section echo 121.79.24.62 and Hroðulf, one peptide possibly being usefull in one situation dosn't sem WP:NOTABLE and the section seemed a lot like advertising. CombatWombat42 (talk) 15:56, 28 January 2014 (UTC)

Proposed merge with Peptidergic

Adjectives are generally not suitable article titles. Best merged to Peptide with minimal definition. No need for superfluous stubs. --Animalparty-- (talk) 20:04, 21 October 2014 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Peptide/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

As far as my recollection goes of my biotechnology courses in college, this information is accurate. However, it is too scientific and uses too much terminology for the common person who may be interested in purchasing peptides for health reasons. A listing of which peptides are produced naturally in the body and which are ingested from food would be most useful. Especially if you can list some food sources of these peptides. If I remember correctly, quinoa (I am not sure if I spelled that correctly) which many people think is a grain (but is actually a relative of leafy green vegetables like spinach and chard have all of the amino acids required by our bodies (or at least that was true 10 years ago) to produce the correct peptides for the body to produce all of our required proteins. That is very very valuable information especially when you consider the importance of protein and the new research about protein and disorders.

Last edited at 14:06, 16 March 2008 (UTC). Substituted at 02:37, 30 April 2016 (UTC)

Dispute: Peptide classes

The section entitled "Peptide classes" begins with the (unreferencced) statement, which I dispute: "Peptides are divided into several classes, depending on how they are produced:

• Milk peptides Two naturally occurring milk peptides...
• Ribosomal peptides are synthesized by translation of mRNA...
• Nonribosomal peptides are assembled by enzymes ... glutathione.
• Peptones are derived from animal milk or meat digested by proteolysis....
• Peptide fragments refer to fragments of proteins that are used to identify or quantify the source protein.."

Maybe a dairy person got a hold of this article, but the idea of near equivalency of ribosomal peptides vs "milk peptides" seems to be WP:UNDUE. My guess is that there are

• ribosomal peptides
• the rest (degradation products, glutathione, odd and ends).

It would be helpful if a biochemical expert looked over this section. --Smokefoot (talk) 23:49, 3 September 2018 (UTC)

@Smokefoot: I agree with this. It seems to a pretty random assortment. Probably ribosomal, protine-derived, and non-ribosomally synthesised. I've emailed a few peptide researchers from different specialisations to get some opinions of how to update the page. T.Shafee(Evo&Evo)^talk 11:17, 7 September 2018 (UTC)

where do you mention albumins?

I always thought that albumins are complexes of several proteins — Preceding unsigned comment added by 86.38.242.213 (talk) 18:44, 27 February 2020 (UTC)

peptide bioregulator

peptide bioregulator or bioregulator peptide --What is this? It is being hyped as an anti-aging item. If this is more than just a scam or fringe idea, the article should discuss this. In fact, the Wikipedia article on one of them, epitalon, seems to say that it is a legitimate research concern. 2600:6C67:1C00:5F7E:2C52:C3AF:FEAF:5B1F (talk) 14:09, 8 October 2022 (UTC)