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)

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)

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)

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.