Talk:Tyrosine

Polar/Non-Polar

This discussion has already taken place on the Amino Acid page, so I won't repeat it here.

Well? This strange caveat should be mentioned in the article (I don't understand it myself, so I'm afraid to edit it in) or there should, at least, be consistency between the two pages. Thanks. --Meta 3:07, 20 Jan 2011 (UTC) —Preceding unsigned comment added by 204.140.154.86 (talk)

Questions

Has anyone ever tried or heard of using tyrosine to help darken the mouth pigment in dogs? What is the pKa of tyrosine? This should be listed on the information page.66.42.177.162 (talk) 00:08, 1 April 2011 (UTC) Does tyrosine accumulate in the body (organs) or is it water soluble?

I concur that all pKA's should be listed on every amino acid. Biochemist textbooks do the same. 2A02:8388:1600:6900:BE5F:F4FF:FECD:7CB2 (talk) 09:17, 20 September 2015 (UTC)

metabolism?

It'd be nice to see some more information on the metabolic effects in humans. I see this is included in certain energy drinks, so it would be good to know it's effect. The current article has little detail.

You can enhance your vigilance a little bit, if you swallow l-tyrosine pills. 500-1000 g are the right dose. Tyrosine is changing in adrenalin and melanin. Also it gets metabolize in hormones for the gland of thyroid. Your blood.pressure gets enhanced! --Fackel 20:47, 30 May 2006 (UTC)

-->I think you mean 500 - 1000 milligrams

--> lol, yeah we may have lost a couple of the more trusting wikiers due to that mistake...

Medical usage

What medical uses are there for tyrosine? I also read that it can promote the division of cancer cells, especially malignant melanoma.

Not really... since it's an essential amino acid it is absolutely required by the human body. You might be talking about tyrosine kinases, enzymes that make the tyrosine phosphorylated (adds a phosporus). That would be a good article to link to from here. --Antorjal 05:00, 5 September 2006 (UTC)

Tyrosine is NOT an EAA. As the article states it's synthesized from phenylalanine. I know this is old but I felt this should be stated so no one gets confused. DriverDan (talk) 18:45, 6 June 2009 (UTC)

Tyrosine is very much a conditionally essential amino acid. Basically, any substantial source of stress can make tyrosine very essential. As such, tyrosine and acetyl tyrosine both are popular supplements. Even so, it's useful only if the relevant cofactors for its utilization are handy. --IO Device (talk) 07:05, 5 December 2014 (UTC)

I found out that tyrosine helps in nemaline myopathy. I think this info should be added as a medical use. I am looking for the info on such usage but there seems to be no other info except just stating this fact that it helps. But the question is why it helps? Maybe someone has an idea... — Preceding unsigned comment added by 83.11.125.35 (talk) 23:47, 25 November 2011 (UTC)

Enzymatic hydroxylation to give m- and o- isomers??

The current graphic has something about "enzymatic" hydroxylation to give ortho- and meta-isomers. I dont know of any evidence for this hydroxylation being directed by enzymatic processes vs some normal free radical degradation. So I am questioning the validity of the graphic.--Smokefoot 22:21, 22 October 2007 (UTC)

• I just updated the graphic based on the previous version. Perhaps the graphic is not as clear as it should be, but it should be interpreted as enzymatic oxidation leading only to the para isomer (this needs to be verified) whereas free radical oxidation (represented by HO^.) leads to ortho and meta (as well as para). Boghog2 22:26, 22 October 2007 (UTC)

• I revised the figure to make it clearer that enzymatic oxidation by phenylalanine hydroxylase only refers to the top reaction. The second and third arrows refer to free radical oxidation. I hope this eliminates the confusion. Cheers. Boghog2 06:54, 23 October 2007 (UTC)

daily dose?

Suggests (without citation) 100mg/kg per day, then says this is equivalent to 500-1500mg per day. So the average adult wieghs between 5kg and 15kg? Either a typo in the dose or in multiplying the dose up for the daily amount. Also, since it claims that the dose/kg is supported by literature this shouldnt be included without a citation.172.201.254.138 11:37, 1 December 2007 (UTC)

• The 500-1500mg per day is the dosage suggested by manufacturers. The dosage of 100mg/kg per day appears in clinical studies. I added citation of clinical study to treat depression with tyrosine where that dosage was used.--Nawojka (talk) 12:41, 26 March 2008 (UTC)

That just made it confusing - so I've moved the clinical dose sentence down a bit to make it less confusing. - Rod57 (talk) 06:03, 12 January 2016 (UTC)

And I've added {{cn to get some sources. Sadly the article doesnt seem to say anywhere how much we use per day or how much we make each day to compare with the 500-1500mg/d mentioned. - Rod57 (talk) 06:03, 12 January 2016 (UTC)

I've added a factual disputation regarding the listed daily dose. The first sentence strongly implies that its given figures are supported by the Dietary Reference Intake (DRI). What's included here doesn't match the cited article, and the article cited is in no way authoritative; in fact, the DRI does not have any guideline for Tyrosine as far as I've been able to find. Naptastic (talk) 23:04, 28 August 2017 (UTC)

Metabolic requirements and synthesis

How much do we use per day (and for what) and how much we make each day ? Is it needed to make thyroxine (as some claim) ? - Rod57 (talk) 06:03, 12 January 2016 (UTC)

Dietary sources

This is just a list - based on differently ordered list on a webpage that doesn't seem to give a ref for the dietary info.
Can we a have a small table with mg/kg or mg/serving for the best sources ? - Rod57 (talk) 06:03, 12 January 2016 (UTC)

... For now I've just noted egg white and lean meats but we need better refs. - Rod57 (talk) 06:40, 12 January 2016 (UTC)

Cocaine and Tyrosine?

I have recently added a line about Cocaine and Tyrosine, suggesting that taking Tyrosine after using Cocaine can reduce the "hangover" and depression effects associated with Cocaine usage This addition was deleted, and I am not sure why I have seen it used many times and produce positive results

I believe that this is an important piece of information, and that it is relevant, I was wondering if anybody objects that I will add it again?

it is a problem to talk about Drugs?

Cocaine stimulate the creation of Dopamine. and Dopamine creation uses tyrosine, and the body has limited ability to create tyrosine. Most Cocaine users don't eat regularly, and as a result lack the Tyrosine. user:Vishvash —Preceding comment was added at 00:20, 16 January 2008 (UTC)

Would it be useful in helping people to withraw from and stop using cocaine if they are addicted? —Preceding unsigned comment added by 69.120.107.230 (talk) 05:05, 28 January 2008 (UTC)

Casein

If tyrosine "is found in large quantities in casein," then why is there no mention of tyrosine in the casein article? I think there's a difference between saying that tyrosine is "found in large quantities in casein" and "tyrosine was obtained as a product of the degradation of the protein casein," as the source says. Also, I see no justification for the claim that tyrosine is found in "large quantities" in casein. I'm removing that part immediately. svadhisthana (talk) 20:41, 17 August 2008 (UTC)

CONTRADICTIONS IN MEDICAL USAGE

This section of the article contradicts itself and is very unorganized. Could someone please organize this section in a way that says: "Support For Tyrosine" and "Support Against Tyrosine" ? It's clear that this section is arguing with itself. It's not unfair and it's not fair, it's just confusing and tedious. Thanks.

What?

Tyrosine... "has little if any effect on mood.[10][11][12] The effect on mood is more noticeable in humans subjected to stressful conditions" This contradicts itself. It is almost like saying "It has no effect on mood. The effect on mood is more noticeable..." 109.153.85.226 (talk) 13:42, 12 March 2012 (UTC)

Is the 3D image correct? There's a Nitrogen with 4 bonds and no Hydrogen at the end. — Preceding unsigned comment added by Elsurexiste (talk • contribs) 23:10, 14 June 2012 (UTC)

Comparison with amphetamine

Tyrosine seems very close to the structure of amphetamine. It would be interesting to see a study seeing if it has similar effects as amphetamine does. Havabighed (talk) 06:47, 5 July 2012 (UTC)

There isn't really that much of a similarity. In any case, no such study is needed because the effects of both substances are well known already. Tyrosine requires a very high dose, i.e. multiple grams. Even acetyl-tyrosine, which is potent, still needs hundreds of milligrams. Amphetamine requires a much smaller dose. Secondly, unlike amphetamine, regular tyrosine use leads to very rapid development of tolerance to it. Tyrosine works for just a few hours, whereas amphetamine works for many more hours. Tyrosine requires numerous cofactors whereas amphetamine is more independent. Tyrosine is in part used to synthesize dopamine. In contrast, amphetamine in part works by reuptake inhibition of dopamine, i.e. in a remarkably different way. --IO Device (talk) 06:58, 5 December 2014 (UTC)

Diagrams

The ball-and-stick representation doesn't seem to tally with the structural depiction. In particular, the bit that's supposed to be NH₂ has 3 hydrogens on it. — Preceding unsigned comment added by 194.39.218.10 (talk) 15:07, 22 October 2012 (UTC) Sorry, scrub that. I just looked up zwitterion! — Preceding unsigned comment added by 194.39.218.10 (talk) 15:10, 22 October 2012 (UTC)

They are two different ways of depicting the same compound. The first diagram is the typical depiction of an amino acid - with a neutral amino group and a neutral carboxylic acid. But since the amino group is a base and the carboxylic group is an acid, in reality the compound is more likely to exist as an ammonium carboxylate, as depicted in the second diagram. Neither is wrong, but maybe it would be best to use a consistent style for the 2D and 3D representations to avoid this type of confusion. -- Ed (Edgar181) 15:13, 22 October 2012 (UTC)

How good is this study?

Reference #21 (http://www.ncbi.nlm.nih.gov/pubmed/12381742) Says that Aspartame is used as the placebo.

According to my Google search: Phenylalanine - University of Maryland Medical Center www.umm.edu › ... › Complementary Medicine Aspartame, found in artificial sweeteners such as Nutrasweet, is a source of phenylalanine. People with PKU should not use aspartame. If you are pregnant, ask

Aspartame contains phenylalanine which turns into Tyrosine. My point is that maybe this study might have used a better placebo and may be biased.

EricStruble (talk) 02:10, 27 February 2013 (UTC)Eric Warren Struble

L-Tyrosine possible uses Thyroid supplement

Wikipedia thyroid hormones "(T3) and (T4) are Tyrosine-Based hormones produced by the thyroid gland" I think there is some important information here about possible uses other than supporting synthesis of brain neurotransmitters. But I don't see any such information in this article about Tyrosine and Thyroid hormones. Please post a reply I am looking for a Thyroid supplement because thyroid cancer runs in my family.urName (talk) 16:51, 31 July 2013 (UTC)

Commercial Synthesis

There needs to be a section on how the Tyrosine Supplements are made. 2602:306:C518:6C40:F04C:9D27:545:1601 (talk) 16:59, 10 January 2014 (UTC)

Betaine section

There is a 'Betaines' section in the wiki page but no text in it whatever. That's confusing.

108.210.118.83 (talk) 04:57, 2 October 2014 (UTC)

I have now removed it. -- Ed (Edgar181) 12:43, 2 October 2014 (UTC)

Molecular Formula

What's the molecular formula?
Eg: Phenylalanine has a chemical formula of C9H11NO2 but a molecular forumla of C6H5CH2CHCOOH
~ender 2014-10-06 5:59:AM MST — Preceding unsigned comment added by 71.223.87.212 (talk • contribs) 13:01, 6 October 2014 (UTC)

for the condensed formula see here Jytdog (talk) 13:16, 6 October 2014 (UTC)

OP posted this on several amino acid pages; please see discussion here: Talk:Tryptophan#Molecular_Formula Jytdog (talk) 14:22, 6 October 2014 (UTC)

Chemical Attributes

I think it would be nice if all amino acids have a short article about their "chemical attributes". It is already partially covered such as by stating that it has a more polar -OH group, while still being an aromatic amino acid. 2A02:8388:1600:6900:BE5F:F4FF:FECD:7CB2 (talk) 09:16, 20 September 2015 (UTC)

Structures

I added an image of L-tyrosine at physiological pH. I thought this to be more biologically relevant and better suited to learning the amino acids and their structures. I deleted the image of the 3-D structural image. I thought this to be irrelevant and not helpful. I moved the image of the neutrally charged tyrosine to the second box and added the zwitterionic form of tyrosine at the top. I also added captions to the images. AidaGhorbani (talk) 05:29, 10 December 2015 (UTC)

Solubility

It should be noted that tyrosine is actually much LESS soluble in water than phenylalanine, due largely to the fact that Tyr's phenolic -OH participates in hydrogen bonding with the carboxyl group. The Merck Index cites these solubility values: Tyrosine – 0.45 mg/mL; Phenylalanine – 29.4 mg/mL. — Preceding unsigned comment added by 2601:240:C400:1D20:5182:F5FA:5F6A:C22B (talk) 14:24, 6 October 2016 (UTC)

Could somebody add Merck Index citations for this? I am not sure how. — Preceding unsigned comment added by 73.208.171.189 (talk) 14:54, 6 October 2016 (UTC)

Citation 7 is broken link

As title. Also, from the "Dietary requirements and sources" section, the RDA of phenyl+tyrosine being 42 mg per kilogram contradicts the Phenylalanine page's "Dietary recommendations" figure of "For phenylalanine plus tyrosine, for adults 19 years and older, 33 mg/kg body weight/day" 46.253.188.8 (talk) 12:26, 24 February 2023 (UTC)

the largest study on tyrosine intake in humans

Under the section of Medical use/research I have updated the section with the largest study on tyrosine intake in humans. The study carried out on 398 healthy subjects, in a 3 years follow-up, found and replicated direct associations between tyrosine intake, reduced grey matter aging, faster visual attention and greater integrity of the Locus Coeruleus. I believe that this study published Journal of Nutrition, Health and Aging by Springer Nature should be acknowledged since it is a milestone in the understanding the intricate neurophysiology of diet, cognition and neurodegeneration. This the text myself and @Tosha Langue have edited. Unfortunately, with no objective reason there is a troll account named @Bon courage which continuously deleted this threatening to block me. I hope other scientists like me will help in transparently and objectively acknowledge such scientific development.

A 2023-year MRI study carried out on 398 healthy individuals linked habitual dietary tyrosine intake to greater total brain mass, better visual attention, and reduced grey matter degeneration, suggesting that this amino acid plays a role in cognitive reserve. PGRE89 (talk) 21:27, 25 March 2024 (UTC)

Totally agree, it is a great study, go ahead DRnabuccodonnosor (talk) 21:35, 25 March 2024 (UTC)

The study has high valence and the methodology is extremely comprehensive and detailed, uncommon piece of science. I would specify in the text the 3 years follow-up since it should be mentioned.

(most of wikipedia "rulers" act in a very questionable fashion while having no formal education in the matter they "despotically rules". We should all do something against this). DonalDhu (talk) 21:54, 25 March 2024 (UTC)

@PGRE89, welcome to Wikipedia! FYI, you’ve reverted twice, and the other user have reverted your edits three times already. If they reverted one more time in 24 hours, they are in violation of our WP:3RR policy and may be subjected to a block. That said, the source you want to use may not be an ideal one that fully compliant with our sourcing guidelines (in general, we prefer reviews to preliminary primary studies). I suggest you add the source to the “External links” section. BTW, we welcome expert editors. Please don’t be discouraged by the reverts and warning :-) Best, --Dustfreeworld (talk) 22:07, 25 March 2024 (UTC)

Thank you for the appropriate and reasonable reply. I appreciate it. I can understand that reviews would be preferable, but I see a lot of very small and preliminary studies mentioned in this page about tyrosine, I do not see why the largest and longest study on tyrosine can not be listed here... should we delete all the others study? I do not think so PGRE89 (talk) 22:12, 25 March 2024 (UTC)

Well.. basically the only one most important rule here is ignore all rules (though I don’t think that includes ignoring civilly rules). Yes if you read carefully, our sourcing guidelines (MEDRS) do allow us to add the main conclusion of a primary study to the article, but again, it’s not preferred. For existing content, we tend to preserve them. If we find any statement that we don’t agree and doubt about its accuracy, we usually tag them for improvement. Aside, if there’s editor that has such “strong feeling” about your addition, they may have their reasons and we may also need to address their concern and consider slowing down our editing, or as I’ve already suggested, add the research to the External links section instead :-) --Dustfreeworld (talk) 22:27, 25 March 2024 (UTC)

SPI has been filed. It is quite obvious that PGRE89/DRnabuccodonnosor/PGRE89 are the same user or heavily related. Psychologist Guy (talk) 22:31, 25 March 2024 (UTC)

... --Dustfreeworld (talk) 22:36, 25 March 2024 (UTC)

Though I edited that text, I cannot join the consensus. As I understand the rules allow to include primaries studies on terms of total and not distorted understanding of their meaning by readers. I have noticed that there are the same primary sources included in the subsection, so I renamed the subsection in order to enhance readers' understanding. That had been noticed and validly corrected by Psychologist Guy. I see no reason in simple saturating Wikipedia with primary medical sources, by no means. Nor External links (Further reading) neither in-line citations. For original researches, Wikimedia has the other project, but in there you need to be absolutely honest too. Tosha Langue (talk) 01:52, 26 March 2024 (UTC)

• Looks like we've got a nasty sock-puppet trying to spam unusably poor primary research authored by ERG Plini into Wikipedia. Should probably be blocked as WP:NOTHERE as this is already a time suck. Bon courage (talk) 02:12, 26 March 2024 (UTC)

• Note this issue has been raised at WP:ANI#"you are censoring me in a fascist way". Any LTA experts in the house? Bon courage (talk) 03:50, 26 March 2024 (UTC)

  You were most likely right, @Bon courage. Indirect signs were pointing at that it was not just a newcomer who accidentally input a bad source. And the source is bad indeed. It is a paid access article, and judging on the abstract is not placebo controlled, and not blind study. It will barely be included in any good review. I must review sources more painstakingly. Thanks! Tosha Langue (talk) 04:21, 26 March 2024 (UTC)

  I've found an open access to the article, and it has not become better, despite the authors almost acknowledged the limitations of their study. Sigh... Tosha Langue (talk) 07:10, 26 March 2024 (UTC)

  To be clear it's:

  • Plini ER, Melnychuk MC, Harkin A, Dahl MJ, McAuslan M, et al. (2023). "Dietary Tyrosine Intake (FFQ) Is Associated with Locus Coeruleus, Attention and Grey Matter Maintenance: An MRI Structural Study on 398 Healthy Individuals of the Berlin Aging Study-II". J Nutr Health Aging. 27 (12): 1174–1187. doi:10.1007/s12603-023-2005-y. PMID 38151868.

  which is open access. Any WP:PAYWALL wouldn't matter, but this falls afoul of WP:MEDRS. Wikipedia is meant to be reflecting accepted knowledge, not novel research. Bon courage (talk) 07:29, 26 March 2024 (UTC)