Talk:Glycine

Photography and Glycine
This does not belong in the category of photographic chemicals. Nowhere in the article does it mention photography, or its use in film making, or any other sort of chemical relation to photography in any way, shape or form. I'm removing it from this category as per the reason I just gave. Cernen Xanthine Katrena 10:40, 23 January 2006 (UTC)
 * I have removed the Glycin redirect and replaced it with a Glycin article, as Glycin and Glycine are two different things entirely. Cernen Xanthine Katrena 19:03, 23 January 2006 (UTC)

Glycine a zwitterion?
Is glycine a zwitterion? If so, then there is incongruity as glycine states that it is non-polar, but zwitterion suggests that it is polar. Anyone know? Ydnagaj 20:29, 6 February 2007 (UTC)


 * I note that an anonymous editor changed polar to nonpolar in November, I just changed it back. I'm an organic chemist, not a biochemist, but as far as I know all standard amino acids are zwitterions, at least in aqueous solution.  I assume that the term "polar amino acid" is a relative term, meaning that something like phenylalanine with a hydrocarbon group attached would class as a "nonpolar amino acid" (though still a zwitterion).  Can a biochemist please confirm that I'm not talking through my hat? Walkerma 06:01, 11 February 2007 (UTC) While I am no biochemist, I do happen to have a textbook right in front of me. The propteries of glycine are described under the heading "Polar, Uncharged Amino Acids", in Garret and Grisham's Principles of Biochemistry: With a Human Focus ISBN 0-03-097369-4 . "The polar, uncharged amino acids except for glycine contain R groups, that can form hydrogen bonds with water. Thus, these amino acids are usually more soluble that non-polar amino acids." It continues later on "Glycine, the simplest amino acid, has only a single hydrogen for an R group, and this hydrogen is not a good hydrogen bond former. Glycine's solubility properties are mainly influenced by its polar amino and carboxyl groups, and thus glycine is best considered a member of the polar, uncharged group." Hybrid04 05:44, 6 March 2007 (UTC)

While free amino acids are Zwitterions, a glycine residue in a peptide has no charge. Biochemists typically are studying the glycine residue in proteins. Clasifying R-groups of amino acids by properties is useful for memorizing and learning, but not completely accurate. For example, Tyr is typically classed as nonpolar, but it has hydroxyl group as well. Glycine, lacking any R group, doesn't really fit into a classification. The polar, uncharged group works best for Gly since side chains in this group do not participate in ionic or hydrogen bonding interactions, which is true for Gly. Qchristensen (talk) 02:59, 2 November 2008 (UTC)

Some thoughts: glycine <-> glycine
1. I am not a chemist.

2. I am confused: ...


 * "it [glycine] is synthesized in the body from other metabolites, including glycine". The way this comes out sounds a bit funny (no offense), at least to me - what would be the energetic gain of resynthesis? glycine -> glycine?


 * Also, the language could be improved a little. Eg. "Glycine is [a] unique amino acid that is not optically active." However, I am uncertain whether this sentence is relevant - it seems to have resulted from a discussion on the talk page (I haven't checked history). What it is not is not all that interesting, but I am sure a biochemist could enlighten (pun intended) me on the importance of the difference between photoreactive amino acids vs. non-reactive, perhaps for another wiki article (hint: link).


 * Given prior discussion on the talk page, perhaps "...should not be confused with glycin" or similar could be included in the very beginning as a note with a link.

I have not made any edits, these are just thoughts. I leave that for the chemists.

3. Overall, the article is an interesting read ranging from the neurochemical function in the brain to the possible astrochemical occurence in space.

4. At least one of my four comments is useless.

In response to 2: I agree, the first point makes no sense. Changing the last glycine to serine does. Optical activity results from chirality, so it would be more to the point to state that glycine is not chiral, unlike all the other biological amino acids. Qchristensen (talk) 03:06, 2 November 2008 (UTC)

Logical fallacy in the section "Presence in the Interstellar medium"
In the section "Presence in the interstellar medium" the statement is made that if glycine is found in the interstellar medium, then "[This] finding would indirectly support the idea of panspermia, the theory that life was brought to Earth from space." For this assertion to be logically consistent one must presuppose that this glycine was produced by, or was the progenitor of, a living entity which predates life on Earth which was then brought to Earth. No evidence has been cited to support these predicates.

I am removing the logically inconsistent statements from the article. Mtiffany71 01:30, 29 June 2007 (UTC)

Globalize/US
Tagged for these reasons: -- B.D.Mills  (T, C) 01:25, 24 June 2008 (UTC)
 * Only US manufacturers are presented as examples.
 * Only US import tariffs are mentioned. There is no mention of any import tariffs for any other country.

I'm removing the tag - it seems an overreaction. The problem (if any) is minor, not systemic to this article. --Rifleman 82 (talk) 03:56, 24 June 2008 (UTC)

WikiProject Food and drink Tagging
This article talk page was automatically added with WikiProject Food and drink banner as it falls under Category:Food or one of its subcategories. If you find this addition an error, Kindly undo the changes and update the inappropriate categories if needed. The bot was instructed to tagg these articles upon consenus from WikiProject Food and drink. You can find the related request for tagging here. Maximum and careful attention was done to avoid any wrongly tagging any categories, but mistakes may happen... If you have concerns, please inform on the project talk page -- TinucherianBot (talk) 06:49, 4 July 2008 (UTC)

Structure
I've just updated the 3D images of glycine with data from the crystal structure: CrystEngComm (2008) 10, 335-343.

I know that the tradition on Wikipedia is to depict amino acids as uncharged species, not zwitterions, but there is a problem: glycine only exists as a cation, a zwitterion, or an anion (except in the gas phase). I can't get a crystal structure of non-zwitterionic glycine because there isn't one. So for consistency between images in the chembox, I think we must should draw glycine as a zwitterion alongside the neutral form.

There's also the issue of how to depict carboxylate ions:

or

A section on the structure and protonation states of amino acids is necessary (does one already exist) and it would be good to create a tailor made discussion for each of the the 20 amino acids, with the pKa values and acid-base behaviour of the amino acid in question discussed.

As a start, I've made a diagram:



Ben (talk) 04:41, 17 March 2009 (UTC)

References for the structure of glycine:


 * Gas-phase:


 * J. Am. Chem. Soc. (1980) 102, 7180–7184: "Millimeter wave spectrum of glycine. A new conformer"


 * J. Am. Chem. Soc. (1980) 102, 6566–6568: "Theory versus experiment: the case of glycine"


 * J. Mol. Struct. (1996) 376, 65-81: "The missing conformers of glycine and alanine: relaxation in seeded supersonic jets"


 * J. Am. Chem. Soc. (1995) 117, 2019–2023: "Shape of Glycine"


 * J. Mol. Struct. (1999) 485-486, 225-238: "Molecular structure of a conformer of glycine by microwave spectroscopy"


 * ''Chem. Phys. Lett." (2007) 435, 336-341: "The shape of neutral sarcosine in gas phase"


 * ApJ (1995) 455, L201-L204: "Microwave Spectra, Hyperfine Structure, and Electric Dipole Moments for Conformers I and II of Glycine"


 * J. Mol. Struct (1991) 246, 257-266: "Main conformer of gaseous glycine: molecular structure and rotational barrier from electron diffraction data and rotational constants"


 * Jmol models of glycine in the gas phase: http://benjamin-mills.com/chemistry/structures/gly-HF/gly-HF.html


 * In solution:


 * J. Chem. Phys. (2006) 125, 114511: "Molecular dynamics simulation of glycine zwitterion in aqueous solution"


 * J. Am. Chem. Soc. (1984) 106, 1945–1950: "Conformational energy of glycine in aqueous solutions and relative stability of the zwitterionic and neutral forms. An ab initio study"


 * J. Phys. Soc. Jpn. (2001) 70, Suppl. A, 365-367: "Hydration Structure of Glycine Molecules in Aqueous Acidic Solutions"


 * Anal. Chem. (2004) 76, 4790–4798: "Quantification of Organic and Amino Acids in Beer by 1H NMR Spectroscopy"


 * Solid glycine:


 * CrystEngComm (2008) 10, 335-343: "Accurate charge density of α-glycine by the maximum entropy method"


 * Acta Cryst. (1972). B28, 1827-1833: "Precision neutron diffraction structure determination of protein and nucleic acid components. III. The crystal and molecular structure of the amino acid α-glycine"


 * Acta Cryst. (2002). E58, o634-o636: "β-Glycine"


 * Acta Cryst. (1980). B36, 115-120: "An experimental study of the influence of temperature on a hydrogen-bonded system: the crystal structure of γ-glycine at 83 K and 298 K by neutron diffraction"

Ben (talk) 20:13, 17 March 2009 (UTC)

---

Hello, I disagree with you. This is true of any amino acid but the drawing of the molecule this way is not only confusing to people not as adept in chemistry, but also is not standard. H2CO3 (carbonic acid) also doesn't exist in the form we commonly think of because it isn't at all stable. Yet we still draw it that way, just like we draw the other amino acids normally - because on paper it makes much more sense. I'm not saying you're wrong, I just don't think it should be put on the wiki in that manner.

However, since your argument is strong, I will try to compromise by putting in both the original structure AND the zwitterion. If you want to write a bit about why the molecule is depicted that way (assuming it's not already there) you may.

Qbmaster (talk) 01:54, 28 April 2009


 * Hi Qbmaster. I am open to suggestions on the issue, I just feel there is an issue. I like your compromise "show both zwitterion and neutral in the chembox" plan. We may need to lead the way by overruling biochemistry standards that are over simplistic in an encyclopedia that covers all science. Who draws carbon dioxide solution as H2CO3 anyway? I'm used to seeing CO2(aq). I don't mind being wrong, but I would like to see the complexity of glycine's structure better discussed, so I'll write a draft section and put it here for criticism.


 * Thanks for your engagement.


 * Ben (talk) 12:09, 28 April 2009 (UTC)
 * added comment on above commentary:


 * "This is true of any amino acid" what is "this"?
 * What is this supposed to mean "H2CO3 (carbonic acid) also doesn't exist in the form we commonly think of because it isn't at all stable." We routinely draw compounds that are unstable. (anyway, unstable with respect to what?). I think that (HO)2CO is quite abundant.
 * "since your argument is strong, I will try to compromise" Implies someone is in control here - you'll try to compromise? Also we are not looking for compromise (which smells faintly of mediocrity) we are seeking consensus.
 * I vote against delocalized image of carboxylates, too complicated for my tastes, but I dont feel very strongly. But that is better than two resonance forms.--Smokefoot (talk) 12:29, 28 April 2009 (UTC)

Thanks for your comments, Smoke. I think "this is true of any amino acid" is about the existence of zwitterions in solid and liquid, but neutral in the gas.

The carboxylates issue troubles me a little. The delocalised description is too complicated for a general audience, but the localised description could be misleading - we could go localised and just hope that anyone who cares about the detail will read about carboxylate resonance elsewhere - or we could go localised for the most part, but add a note and link to carboxylate.

Ben (talk) 12:55, 28 April 2009 (UTC)

Structure of glycine
Dear Manager In the Picture (Molecular Show) of Glycine you show the Blue Nitrogen in wrong form because Nitrogen has a three capacity and after connection to Carbon must be Has two Hydrogen but you show this nitrogen Connected to Carbon and has one Hydrogen excess. Please Check this subject and informed me by email. Best regards Arash Goshtasbi Asl Senior researcher of Petrochemical Engineering from Iran ArashGoshtasbi
 * The pictures can be confusing because some show the ammonium tautomer of glycine and some show the form where the acidic proton is on the carboxylate. In the ammonium tautomer, nitrogen has four bonds instead of three + the lone pair of electrons.

--Smokefoot (talk) 04:42, 15 August 2009 (UTC)

Gly side chain
Are you sure Gly has two H as its 'side chain'? I think every alpha-aminoacid has an alpha-C bound to four groups or atoms: COOH, NH2, H and side chain. This H, present in every alpha-aminoacid, is not a part of the side chain. So, if I'm not wrong, Gly has one H side chain. Miguelferig (talk) 20:29, 9 July 2011 (UTC)

GEO Web site addition is spam
The GEO web site was added as a reference and as an external link. Looking at the web site, it only indicates that they supply glycine, not how they supply it, therefore its inclusion as reference 9 is flawed. The inclusion of the web site in the External Links is strictly spam. Both need to be removed. I have removed them once and was reverted. WP:COI perhaps?JSR (talk) 16:01, 4 October 2012 (UTC)

Structure - again!
I've removed this structure for various reasons. It is very dispiriting to see comments (above) that the delocalized structure might be too difficult. For whom? The fact is that in the zwitterionic form the two C-O bonds are identical in length etc. This is independent of any particular bonding theory. Therefore it is not satisfactory to show a structure with one single bond and one double bond. At the very least, in valence bond theory, the two canonical forms should be shown as being in resonance. Personally I prefer the dotted line shown in the info box.
 * 1) It's in the wrong place
 * 2) It conflicts with the structure at the top of the article
 * 3) The caption is nonsense
 * 4) The carboxylate is not delocalized

The nature of glycine in aqueous solution is that there is an equilibrium between the two forms, with the zwitter ion predominating. The ratio of concentrations of the two microspecies is independent of the glyine concentration and of pH; it's simply the equilibrium constant for isomerization. Petergans (talk) 18:02, 15 September 2013 (UTC)

Role of Glycine in human nutrition The article needs to state whether glycine is or is not an essential amino acid, and what that means.75.164.86.109 (talk) 17:25, 20 March 2014 (UTC)TheNovelist

synthesis from threonine
Should the biosynthesis section not mention something about glycine's synthesis from threonine?

External links modified
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Glycine: Improves gastric absorption of drugs? //Serves as pH buffer in medicines and other stuff?
Wikipedia now says: "Certain drug formulations include glycine to improve gastric absorption of the drug.[25]"

The link 25 is broken. Can you find more information of this?

Also it would be nice to learn more about this buffering: "Glycine serves as a buffering agent in antacids, analgesics, antiperspirants, cosmetics, and toiletries".

"It serves as a buffering agent, maintaining pH". 91.155.24.127 (talk) 07:15, 20 September 2017 (UTC)

Not to be confused with Glycerol
I confuse Glycine with Glycerol Speed57 (talk) 16:18, 21 February 2018 (UTC)

Can't understand the structure
I dont understand how is there only 1 hydrogen atom but there are 2 atoms not in the structure. Can someone tell me how is this possible? Muonium777 (talk) 06:30, 2 November 2021 (UTC)

Merger proposal
proposes that Glycine hydrochloride be merged into Glycine. Reba16, to start the discussion please describe why you think the articles should be merged. Mdewman6 (talk) 00:30, 3 November 2021 (UTC)

The discussion was initiated at Talk:Glycine_hydrochloride where Reba16 writes:
 * In general, I don't think Wikipedia needs separate articles for a chemical compound and one of its salts, unless there is significant independent notability. That is not the case here.  In addition, I agree with User:Smokefoot's comment that the article is not suitable for mainspace (it hasn't changed much since that 2012 comment).  Therefore, I suggest merging into glycine (or just redirecting there).

–Mdewman6 (talk) 06:43, 3 November 2021 (UTC)
 * Merge. The only claim of "notability" (a WP requirement to have an article) is that it "allosterically regulates NMDA receptors". But it's uncited (WP:V is WP policy) and it doesn't seem like this would be specific to the HCl salt. DMacks (talk) 00:22, 1 December 2021 (UTC)


 * I have now merged to the two articles. Reba16 (talk) 23:54, 10 December 2021 (UTC)

Pyrolysis
Pyrolysis of glycine or glycylglycine gives 2,5-diketopiperazine, the cyclic diamide

Pyrolysis usually includes a breakage of C-C bonds. This is simply a second condensation step. --46.232.229.52 (talk) 14:40, 28 February 2022 (UTC)

sulfamic acid
sulfamic acid is simpler 59.102.93.132 (talk) 01:00, 30 March 2022 (UTC)

Protein
Why Ghycine Attach With Carboxyl Acid and Amino Acid 182.189.213.48 (talk) 16:08, 9 June 2022 (UTC)

Please review my edit and check it for grammar
I have added content to Glycine. Please review and check it for grammar. Also I wanted to add the following: "Wide uncontrolled use of benzoates as food preservatives has raised healthcare concerns. Researcher hypothesized that depletion of the body glycine supply during benzoates exposure may interfere other biological roles of glycine or peculiarities of the metabolic pathway itself that depend on the type of toxic organic acids, may influence liver cancer, musculoskeletal development, and mitochondrial energy metabolism" But I hesitate in references quality. Tosha Langue (talk) 14:51, 27 January 2024 (UTC)
 * I do not recommend adding the "Wide uncontrolled use of benzoates as food preservatives ..."  First of all, its hyperbole, to be polite.  Second is the flag of bullshitters:  "Researchers" say this and that.--Smokefoot (talk) 16:14, 27 January 2024 (UTC)
 * @Smokefoot, understood! Tosha Langue (talk) 16:21, 27 January 2024 (UTC)