Talk:Methionine/Archive 1

untitled
Hi, I just edited the main page, sorry I should have asked first, I thought that some foods on the list of rich sources of Methionine were wrong - oranges have comparatively little Methionine as do most fruit and veg compared to nuts or meat. I've based this pre-dominately on this source - http://www.nutritiondata.com/nutrient-search.html (the menu can be used to look at sources of Methionine in the various food groups).

--134.225.163.117 16:19, 29 March 2006 (UTC)

According to my biochemsitry text, the pKas for Methionine are 2.28 and 9.21, giving an isoelectric point of 5.745. Here, the pKas appear to be incorrect, and they do not give the correct IP of Met.

--Priss 05:06, 10 October 2005 (UTC)

You know, even if methionine is incorporated into the N-terminal position of a newly synthesized protein, there is no guarantee that in the mature product, it is still the N-terminal amino acid. Some proteins and peptides (for example, insulin) are subjected to the actions of proteases before assuming their mature form. Some proteins have leader sequences that allow them to be transported to their place of action, and the leader sequence is cleaved once transport takes place. David M

Where I work, the people in another lab a few years were trying to label a protein by incorporating sulfur isotope labelled methionine. They tried and tried, and got nowhere... turned out the protein had no methionine. Malcolm Farmer

"Together with tryptophan, it is the only amino acid needing three bases to encode (nucleotide codon AGT for methionine)."

This makes no sense to me, can someone explain.

Jedi Dan 18:32 Apr 23, 2003 (UTC)

I think I see what the writer intended... I've rewritten it to make it clearer. (I hope) 147.188.60.51

Does methionine occur in positions other than the N-terminus?

Thanks, has_no_nick

Reply to self:

Yes, it occurs at other positions in some proteins.

I'll just add that on the page. Regards.

"Usually removed"?

Is there any evidence to have the phrase "usually removed by post-translational modification"? If so, can someone put that in. If not, then perhaps the wording shouldn't be as strong (how many proteins in how many species are known to have this phenomenon?).

SMILES
Currently the SMILES is


 * C(N)(C(O)O)CCSC

but shouldn't it be


 * C(N)(C(=O)O)CCSC

? I went ahead and change it but please revert if I'm missing something here. Cburnett 05:06, 19 April 2006 (UTC)

External link request
Hi. Will you put a link to my site on this page? like this: drugs-about.com/ing/methionine.html Drugs and Health Products containing Methionine

Thank you.
 * That website does not appear to meet criteria for inclusion because of its highly commercial content and purpose. Please see the guidelines for external links at WP:EL and WP:SPAM.  Thanks for asking, though, which is a rarity.  Deli nk 17:25, 27 September 2006 (UTC)

Moved from comments page
Hi, I would like to know information about SAMe (s-adenosyl-methionine) and in particular, claims that it can aid in recovery of depression. - 09:21, 29 March 2007 60.242.72.197 —The preceding unsigned comment was added by Tameeria (talk • contribs) 19:53, 28 April 2007 (UTC).

DL-methionine
DL-methionine should be mentioned in the article, as it is under this name that this chemical is added to foodstuffs. Badagnani 23:17, 5 August 2007 (UTC)

L-Methionine as wart removal?
I've had a Doctor prescribe this for me a couple of times to help recover from a wart.

Does anything have access to something more official to include as references to add this information to this article?

I found a couple of things from a google search:

http://talesfromthecrib.blogspot.com/2006/04/herbal-remedies-for-everyday-mom.html http://bodyodd.msnbc.msn.com/archive/2008/10/28/1603159.aspx?p=1

I also saw some abstracts on the topic:

http://www.ncbi.nlm.nih.gov/pubmed/5741494?dopt=Abstract http://linkinghub.elsevier.com/retrieve/pii/S0733863505701790

Can we gather enough information to include this in the article —Preceding unsigned comment added by Magicalspirits (talk • contribs) 22:45, 14 January 2009 (UTC)

Methionine restriction
Don't the Methionine restriction facts sound contradictory. What are the real results? —Preceding unsigned comment added by 78.190.134.130 (talk) 14:14, 6 December 2009 (UTC)

Is meat and fish forbidden by law of Lord Vegan ?
I read that fish and meat are very good source, but i get in front a table with only plant source. —Preceding unsigned comment added by 129.16.137.100 (talk) 18:09, 16 June 2010 (UTC)

contradictory statements about rice & beans.
The article is currently self-contradictory: We have this table: Food                  g/100g Beans, pinto, cooked 	0.117 Lentils, cooked 	0.077 Rice, brown, medium-grain, cooked 	0.052

which implies that both rice & beans have among the very lowest in methionine content (rice hitting rock-bottom in the list). Then we have a photo caption:
 * Rice and beans provides a complete protein, the methionine in the rice complementing the proteins in the beans.

I've removed the rice&beans photo, this seemed easiest, given that the table seems to be properly referenced. I hope someone can fix this. linas (talk) 00:44, 7 September 2010 (UTC)

methionine linked to age deterioration
two groups -- those with a BDNF gene that contained methionine, and those with a BDNF gene that did not contain methionine.

http://news.yahoo.com/aging-brains-decline-may-hinge-gene-130406334.html — Preceding unsigned comment added by 75.85.14.106 (talk) 09:32, 26 October 2011 (UTC)

Article spammed by "immortality" pseudoscience
Restriction of dietary methionine to 0 will kill humans. How about that for affecting lifespan? tepi (talk) 20:18, 25 September 2012 (UTC)


 * no presentation of the reverse evidence, the detrimental health implications of dietary sulfur containing amino acid restriction... tepi (talk) 20:31, 25 September 2012 (UTC)

Doesn't qualify as an encyclopedia article.
Probably 95% of people looking up "methionine" in an encyclopedia are interested in it as a nutrient, yet this article starts out like it was cut and pasted from a biochemistry textbook. This is so typical of wikipedia articles on any science subject, and one of the main reasons that one sees so many negative internet comments about wikipedia lately. What ever happened to "too technical"?77Mike77 (talk) 14:52, 29 April 2013 (UTC)
 * Since when did we write articles based upon what the majority of people want to look up? Encyclopedic means covering a topic in its entirety, not focusing on one small aspect, in this case human nutrition. Respectfully, I suggest you make specific examples of how you think the article can be improved rather than expansive statements which rarely lead to improvement in my experience. E.g. if you think a specific phrase or term is too technical and it is not wikilinked or explained in brackets. Unsubstantiated criticisms that content has been cut and pasted from a source (i.e. copyright vio) need to be backed up with evidence. As to "negative comments about wikipedia", I think its global popularity speaks for itself and doesn't require defense. Lesion  ( talk ) 15:18, 29 April 2013 (UTC)

An encyclopedia article is not supposed to read like an entry in a handbook of biochemistry; the opening paragraph should give an explanation that is not custom-designed for biochemistry majors. Have you ever read an en encyclopedia entry? The only suggestion I could make is to move the opening paragraph to the bottom, and call it Biochemical Details, and write a proper opening paragraph that is readable by the general public - encyclopedias are for the general public, not for specialists; specialists can refer to textbooks and reference handbooks. (Or remove the "pedia" from "wikipedia", since so few contributors know what an encyclopedia is. "Wikiminutiae" would work better for a collection of articles like this one, but that's not likely to happen.) Just make a proper opening paragraph, that would salvage it.77Mike77 (talk) 16:51, 29 April 2013 (UTC)
 * This is because Wikipedia is not a paper encyclopedia. We are supposed to cover topics more comprehensively. See Featured article criteria. Featured and good articles on wikipedia (what editors aim towards) are usually very long compared to the corresponding entry in a traditional encyclopedia. We should not avoid jargon/specialist terms where these are needed to explain aspects of the topic. Where it is used it should be explained. My preference is to wikilink the term and also explain it in general language in brackets. This article could do with some expansion, but I would not dumb it down and remove any content. In the lead most terms are wikilinked already, but a few (mRNA, protein translation) could benefit from at least wikilinking, if not also explanation in brackets. Some of the methionine restriction content is based on primary sources and could be replaced with secondary sources. As per WP:LEAD currently the lead is not summarizing the content of the entire article. More could be added. Quick review of the articles for the other essential amino acids shows that the leads are all written in this style. Suggest comment on WT:WikiProject_Molecular_and_Cellular_Biology. Lesion  ( talk ) 19:34, 29 April 2013 (UTC)

That was a fair comment. It is unfortunate that wikipedia is not an encyclopedia, and I again question why they put the word root "pedia" in a project that is NOT an encyclopedia, but more of a technical database for specialists, presented in a way designed to excude the the sort of general audience that would use an encyclopedia. In the future, when I google a topic, I will be sure to avoid wikipedia if I do not have a Ph.D. in that topic. (Of course, if I had a degree in biochemistry, I wouldn't be googling it in the first place.) I'm not sure what the point of wikipedia is - just something to do? Good luck with it, in any case.77Mike77 (talk) 02:45, 30 April 2013 (UTC)


 * The success of wikipedia is very much related to the fact that it does not follow the format & space restrictions of traditional encyclopedia. If you read the manual of style, if articles are written according to these policies then they are not exclusionary to a general audience. I also question whether traditional encyclopedias avoid technical language and dumb down their entries, I think most are written in the technical language that surrounds the subject of the entry. At least on wikipedia there is the space to explain this technical content in full, which gives it the potential to be a superior reference. Lesion  ( talk ) 16:06, 30 April 2013 (UTC)

This guy was right about it needing a new intro. I wrote a properly sourced encyclopedic introduction that both makes the topic accessible to someone interested and in no way hampers its ability to go into the kind of depth we know and love on Wikipedia. Be aware, such obscurity may be steming from those with a vested interest: If you look at 100g of eggs, for example, you'll find there's nearly 4x as much Methionine as a person needs in a day. It's very likely that someone interested in limiting the knowledge that Methionine is related to cancer is going to want to hide it under jargon that distracts the typical reader. 69.166.35.218 (talk) 20:34, 7 September 2016 (UTC)

Essential aminoacid
In the introduction it is called an essential aminoacid. But in what species? Is it not synthesised by any organism? I find this hard to believe. There is nothing that indicates what species this concerns. From the biosynthesis section I understand that this would include most animals, is it all animals? Should the second sentence be rewritten to: "This nonpolar amino acid is essential in animals." Would that be correct? What about fungi? The biosynthesis section is ambiguous about what organisms other than plants synthesise methionine. PinkShinyRose (talk) 19:24, 6 April 2014 (UTC)

glutathione
None of the sections even mention it! FoCuSandLeArN (talk) 19:11, 9 June 2014 (UTC)

https://en.wikipedia.org/wiki/Methionine#Dietary_sources
This is now very irrelevant. You get zero methionine if you do not eat any protein. Of course if a certain food contains a lot of protein, it also has a lot of methionine!

It would be more relevant to find out, how many percent of protein is methionine. ee1518 (talk) 13:23, 25 December 2014 (UTC)

2 broken links ('External')
In the 'External Links' section, two of the 3 links which refer to external dietary info sites, are broken (sites not accessible)

•	Food Sources of Methionine ->      ["account suspended"] •	Foods containing methionine -> http://www.hcusupport.com/diet.htm        [server not found]

will wohler 50.11.49.114 (talk) 04:37, 27 December 2014 (UTC)

Methionine restriction for immortality &sect; ...
... she's goin' down mang, no way that's gonna stand like it is now. That Titantic of a misplaced POV is takin' on water fast :) Lycurgus (talk) 07:27, 28 December 2014 (UTC)

Vegan diet for methionine restriction in human diet
This paragraph should be removed since it doesn't seem to be true as shown in this observational paper. Restricting methionine intake via diet does not reduce plasma level of methionine and introduces a whole new level of health problems. — Preceding unsigned comment added by 89.16.141.90 (talk) 18:20, 11 June 2015 (UTC)

Standardizing amino acids
There is a lot of inconsistency regarding what information is presented by the introductory paragraph. I think it would be great to standardize this information. As in have all 20 main amino acids follow a common template. Furthermore, the addition of the ionized (native biological state) of the amino acid alongside the historically represented line-angle model would provide a more factual representation of their states

Linnikh (talk) 00:05, 18 November 2015 (UTC)

Weak Sourcing: Methionine - Other uses: Adjusting PH of canine urine to prevent the killing of grass
I'm pruning this claim, and it's weak source from the article. The link given in support is obviously Sponsored Content advertising pet health supplements, while acting under the guise of an informational article. To add insult to injury, this mis-information has been propagated to Wikipedia. Interstellarsurfer (talk) 10:09, 8 January 2016 (UTC)

Adequate intake amounts?
There is a table listing on how much methionine is in certain foods, but nothing in preceding paragraphs to relate those amounts to what humans need each day. --Egmonster (talk) 09:28, 4 February 2016 (UTC)
 * (And by the way, footnote #14, in Methionine, is broken.) --Egmonster (talk) 16:32, 16 February 2016 (UTC)
 * I was able to fix footnote #14, but sorry I can't help with your original question. -- Ed (Edgar181) 17:39, 16 February 2016 (UTC)
 * Mostly-incorrect usage of the helpme. This is more of a topic for discussion rather than a "how can I fix this" (apart from the footnote issue, which was fixed). This page is watched, so please be patient in waiting for a response. Primefac (talk) 01:09, 17 February 2016 (UTC)
 * Thank you, Edgar181. Primefac, please WP:DONTBITE. It's not as if I put up my helpme request after his fix. I added it while editing to flag that broken footnote (beyond my ability to repair) which I spotted while repeatedly checking for any clues or edits relating to my unanswered question from 12 days earlier. But, after this, I vow never to use helpme again outside a user talk page. --Egmonster (talk) 18:45, 17 February 2016 (UTC)
 * , I think you're misreading my statement. You asked for assistance with footnote #14, which was given. Your other concern was not applicable for a one-off helpme request. Thus, I closed it with rationale for why. I'm not sure why you thought that I thought you placed the helpme after the footnote issue was fixed, as that would be a rather silly move (on both our parts). But if throwing your hands up in the air is what you want to do, go for it. Primefac (talk) 19:32, 17 February 2016 (UTC)
 * No, what I want is to use Wikipedia and make it better. It's a year later and this question is still unanswered. How long should I shut up and wait, sir? Egmonster (talk) 17:18, 16 February 2017 (UTC)

Assessment comment
Substituted at 23:47, 29 April 2016 (UTC)

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Wrong models
It seems that both the models are wrong, with a hydrogen atom in the wrong place.--2A00:1028:9192:C0DE:F050:2DDB:28BF:752E (talk) 11:21, 17 August 2020 (UTC)


 * They're not wrong, exactly, it's just that the model is based on X-ray crystallography of solid methionine, which exists as a zwitterion. It's actually the skeletal formula that is something of a fiction - it shows both an acidic -COOH group and a basic -NH2 group. These would immediately react with each other to form the zwitterion.


 * Ben (talk) 17:44, 25 September 2020 (UTC)

Source missing
The sentence "[..], and recent evidence suggests that it may have a greater influence on methionine and homocysteine homeostasis than methionine synthase." is not backed up by any source, yet.

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