Talk:Methionine

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Molecular and Cellular Biology (Rated B-class, High-importance)
WikiProject icon This article is within the scope of the WikiProject Molecular and Cellular Biology. To participate, visit the WikiProject for more information.
B-Class article B  This article has been rated as B-Class on the project's quality scale.
 High  This article has been rated as High-importance on the project's importance scale.
 

This article has comments here.

WikiProject Chemicals / Core  (Rated B-class, Mid-importance)
WikiProject icon This article is within the scope of WikiProject Chemicals, a daughter project of WikiProject Chemistry, which aims to improve Wikipedia's coverage of chemicals. To participate, help improve this article or visit the project page for details on the project.
B-Class article B  This article has been rated as B-Class on the project's quality scale.
 Mid  This article has been rated as Mid-importance on the project's importance scale.
Taskforce icon
This is a core article in the WikiProject Chemicals worklist.
 

This article has comments here.

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[edit]

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[edit]

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[edit]

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 (talkcontribs) 19:53, 28 April 2007 (UTC).

DL-methionine[edit]

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?[edit]

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 (talkcontribs) 22:45, 14 January 2009 (UTC)

Methionine restriction[edit]

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 ?[edit]

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.[edit]

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[edit]

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[edit]

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.[edit]

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 Wikipedia: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)

Essential aminoacid[edit]

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[edit]

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