Talk:Guanine

message: Nothing in the cited article indicates that extracts were taken from bird droppings. In the article, which is from 1944 not 1844, they were from fish scales.
Does anyone have a real source for this?
Hitchings, George H.; Elvira A. Falco (1944-10-15). "The Identification of Guanine in Extracts of Girella Nigricans" (PDF). Proc. Natl. Acad. Sci. USA 30 (10): 294–7. doi:10.1073/pnas.30.10.294. PMC 1078714. . Retrieved 2007-10-18.
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"guano" is what you might be thinking of in that last sentence.  -- dja
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it was mentioned on several web sites, so I put it in.
guano is bat dung to my recollection, tho it may be high in Guanine ... 
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My understanding is that the guanine in fish scales and some dungs is the same as the guanine in DNA, only not polymerized or not polymerized through nucleosides at least...  --128.218.169.187 00:38, 15 Jun 2004 (UTC)
thread_title: Untitled

message: The ring positions are numbered wrong in the guanine image towards the top of the page. —The preceding unsigned comment was added by 140.251.13.35 (talk • contribs).
:In addition to the above comment, 128.12.106.7 says it is backwards: .  So, I've swapped the labels in the image and reuploaded, see .
:Just replying here for posterity's sake. Cburnett 20:53, 18 December 2006 (UTC)
replies: text: Perhaps it should be noted that the numbering of ring positions in Guanidine differs from the generel rules of numbering of heterocyclic compounds. 130.225.102.1 (talk) 07:35, 25 February 2008 (UTC)
thread_title:  Wrong numbering 

message: The previous reaction formula fro Traube's synthesis was obviously ne as described above it. I therefore found another formula for it in another place. It does not correspond to the description above: not 2,4,5-triamino-1,6-dihydro-6-oxypyrimidine, but 2,4,5-triamino-6-oxypyrimidine reacts, as I understand it. I think that the reaction formula ir correct, not the description, but I will make a check before I make that change. Lave 22:34, 7 December 2008 (UTC)
thread_title: Traubes synthesis

message: Is it a lipid  —Preceding unsigned comment added by 96.13.22.49 (talk) 22:38, 17 August 2010 (UTC)
thread_title:  Talk 

message: Substituted at 16:48, 29 April 2016 (UTC)
thread_title: Assessment comment

message: At present this article states:  "In 1656 in Paris, François Jaquin extracted from the scales of some fishes the so-called pearl essence, crystalline guanine forming G-quadruplexes."  No reference is cited for this statement.
A few modern sources repeat this claim, but after much investigation, there is no evidence that Mr. Jaquin's first name was "François".
On p. 109 of Chemiegeschichtliche Daten organischer Naturstoffe (Historical chemical data of organic natural substances) by Rudolf Werner Soukup, he mentions that in 1656, François Jaquin prepared "pearl essence" (Perlenessenz) from fish scales (Fischschuppen).  As his source, he cites:
de Reaumur (1716) "Observations sur la matiere qui colore les perles fausses, & sur quelques autres matieres animales d'une semblable couleur ; à l'occasion de quoi on essaye d'expliquer la formation des ecailles des poissons" (Observations on the matter that colors false pearls, and on some other animal materials of a similar color ; in connection with which one tries to explain the formation of fish scales), Histoire de l'Académie royale des sciences avec les Memoires de Mathematique & de Physique, pour le même Année, pp. 229–244.
Reaumur's article doesn't mention "1656" or "François Jaquin" or guanine.  However, it does explain that imitation pearls were made by rubbing the scales from small fish, called able or ablete or ablette in French (Cyprinus alburnus) and then repeatedly washing them until a viscous liquid results, "essence of pearl", which has the opalescence of pearls.  The imitation pearls were made by placing a drop of the pearl essence in a small glass bubble, coating the interior of the bubble with the essence, and then filling the bubble with wax.
This source — Johann Rudolf von Wagner,Ferdinand Fischer, and L. Gautier, Traité de chimie industrielle (Treatise on industrial chemistry), 4th ed., (Paris, France:  Masson & Co., 1903), vol. 2, pp. 64–65 — states that in 1656 in Paris, someone named "Jaquin" produced pearls by means of the procedure described above.  But there's no mention that his first name was "François".
In some French books of the 16th and 17th century, the word "Frenchman" was spelled both "Français" and "François", so it's possible that someone misunderstood "un François Jaquin" (a Frenchman [named] Jaquin) as "François Jaquin". 
By the way, in 1861 the French chemist Charles-Louis Barreswil (1817–1870) found that "pearl essence" was guanine.  See:  Barreswil (1861) "Sur le blanc d'ablette qui sert à la fabrication des perles fausses" (On the white of ablette that's used in making imitation pearls), Comptes rendus, 53 :  246.
VexorAbVikipædia (talk) 01:33, 10 October 2016 (UTC)
thread_title:  François Jaquin and guanine ?