Talk:Murchison meteorite

Active discussions

Amino Acid ListEdit

I just removed the following list of amino acids found in the meteorite from the Amino acid page:

list of amino acids
Amino Alkanoic Acids

2 Carbon:
Glycine

3 Carbon:
Alanine
b-alanine
Serine
Sarcosine

4 Carbon:
Threonine
a-Aminobutyric Acid
b-Aminobutyric Acid
g-Aminobutyric Acid
a-Aminoisobutyric Acid
b-Aminoisobutyric Acid
N-EthylglycineN,N-dimethylglycine
N-Methylalanine
N-methyl-b-alanine

5 Carbon:
Valine
Isovaline
Norvaline
Proline
Methionine
3-Amino-2-ethylpropanoic Acid
3-Amino-2,2-dimethylpropanoic Acid
3-Amino-2-methylbutanoic Acid
3-Amino-3-methylbutanoic Acid
4-Amino-2-methylbutanoic Acid
4-Amino-3-methylbutanoic Acid
Allo-3-amino-2-methylbutanoic Acid
3-Aminopentanoic Acid
4-Aminopentanoic Acid
5-Aminopentanoic Acid

Amino Dialkanoic Acids


4 Carbon:
Aspartic Acid

5 Carbon:
Glutamic Acid
2-Methylaspartic Acid
3-Methylaspartic Acid
Allo-3-methylaspartic Acid
N-Methylaspartic Acid

6 Carbon:
a-Aminoadipic Acid
2-Methylglutamic Acid

7 Carbon:
a-Aminopimelic Acid

Amino Alkanoic Acids

6 Carbon:
Leucine
Isoleucine
Alloisoleucine
Norleucine
Pseudoleucine
Cycloleucine
2-Methyl-norvaline
Pipecolic Acid
2-Amino-2-ethylbutanoic Acid
3-Amino-2-ethylbutanoic Acid*
2-Amino-2,3-dimethylbutanoic Acid
3-Amino-2,3-dimethylbutanoic Acid*
4-Amino-3,3-dimethylbutanoic Acid*
3-Amino-3-methylpentanoic Acid*
4-Amino-2-methylpentanoic Acid*
4-Amino-3-methylpentanoic Acid*
4-Amino-4-methylpentaoic Acid*
3-methylamine-pentanoic Acid*
4-Aminohexanoic Acid*

7 Carbon:
2-Amino-2,3,3-trimethylbutanoic Acid
2-Amino-2-ethyl-3-methylbutanoic Acid
2-Amino-2-ethylpentanoic Acid
2-Amino-3-ethylpentanoic Acid
2-Amino-2,3-dimethylpentanoic Acid
2-Amino-2,4-dimethylpentanoic Acid
2-Amino-3,3-dimethylpentanoic Acid
2-Amino-3,4-dimethylpentanoic Acid
2-Amino-4,4-dimethylpentanoic Acid
Allo-2-amino-2,3-dimethylpentanoic Acid*
Allo-2-amino-3,4-dimethylpentanoic Acid
2-Amino-2-methylhexanoic Acid
2-Amino-3-methylhexanoic Acid
2-Amino-4-methylhexanoic Acid
2-Amino-5-methylhexanoic Acid
Allo-2-amino-3-methylhexanoic Acid*
Allo-2-amino-4-methylhexanoic Acid*
2-Aminoheptanoic Acid

8 Carbon:
An amino alkanoic acid*

9 Carbon:
Phenylalanine
Tyrosine

D- and L-2,3-diaminopropanoic acid
D- and L-2,4-diaminobutanoic acid
3,3'-diaminoisobutanoic acid
2,3-diaminobutanoic acid
4,4'-diaminoisopentanoic acid

Such detailed info about one specific specimen seems inappropriate for the general amino acid page, and someone reading about the meteorite itself would likely not see it there either. Someone who is interested should consider adding it here, formatting it as a wiki list (or list of sublists, or whatever), adding italics, greek letters, caps/lowercase and other standard chemical typographic conventions, etc. DMacks 18:06, 5 June 2006 (UTC)

Non-linear catalysisEdit

is this paragraph a joke? i hope so: "The catalysis is non-linear, that is proline with an enantiomeric excess of 20% yields a allose with enantiomeric excess of 55% starting from a benzyloxy acetaldehyde in a sequential aldol type reaction in an organic solvent like DMF [5]. In other words a small amount of chiral amino acids may explain the evolution of right-handedness of sugars." —The preceding unsigned comment was added by 143.252.80.100 (talkcontribs) 13:31, 27 July 2006 (UTC).

Are you questioning the science of the amplification (20% leads to 55%), something else about the science, the relevance to the meteorite, or something else? DMacks 14:51, 27 July 2006 (UTC)

I had the exact same reaction when I read that paragraph. Perhaps it makes sense to people in the appropriate field, but even though I come from a field rich in jargon (computer engineering) I think that paragraph needs some serious work. Unfortunately I don't even know where to start. Is it suggesting that some of the unusual "left-handed"(?) amino acids could be creating "right-handed" sugars? If so, maybe just say that?76.126.58.246 (talk) 21:09, 12 August 2010 (UTC)

Trying to clean up the text. It looks too much like a ransom note just now. Kortoso (talk) 21:21, 11 September 2013 (UTC)

See if the new paragraph makes sense. Kortoso (talk) 21:58, 11 December 2013 (UTC)

QuestionEdit

I am seeing a fair number of sources that say that as many as 50 of the Murchison amino acids are not found on Earth. What gives? New chemicals suddenly discovered? Or science writers abbreviating things again? http://www.astrobio.net/exclusive/375/murchisons-amino-acids-tainted-evidence Kortoso (talk) 21:41, 11 September 2013 (UTC)

I am seeing too many assumptions that Murchison and other meteorites are "the source" of these compounds, rather than the more conservative conclusion that it is representative of another celestial body in which organic compounds were evolved. http://www.scientificamerican.com/article.cfm?id=murchison-meteoriteKortoso (talk) 21:51, 11 September 2013 (UTC)

FossilsEdit

http://science.jrank.org/pages/4501/Murchison-Meteorite.html "In 1997, NASA scientists announced evidence that the Murchison meteorite contained microfossils that resemble microorganisms." I can't seem to find a primary source for this however. Kortoso (talk) 19:50, 11 December 2013 (UTC)

Ah, here: http://www.panspermia.org/hoover.htm
Discredited, BTW. Kortoso (talk) 21:01, 11 December 2013 (UTC)
See this on its publisher, the Journal of Cosmology. -BatteryIncluded (talk)

Presolar GrainEdit

Still, is there nothing on the Murchison on a "macro" or structural scale, rather than grinding it up and testing for elements? Kortoso (talk) 22:43, 29 September 2014 (UTC)
No morphology suggesting fossils and there is nothing of astrobiological interest in Murchinson beyond molecules. Cheers, BatteryIncluded (talk) 23:22, 29 September 2014 (UTC)
Well, I'm not bug-hunting here, just looking at what the structure might look like. Here's something, but it might need a translation:
http://iopscience.iop.org/0004-637X/472/2/760
"Transmission electron microscopy (TEM) of ultrathin sections of the spherules revealed that many have a composite structure consisting of a core of nanocrystalline carbon surrounded by a mantle of well-graphitized carbon. The nanocrystalline cores are compact masses consisting of randomly oriented graphene sheets, from PAH-sized units up to sheets 3-4 nm in diameter, with little graphitic layering order. These sheets probably condensed as isolated particles that subsequently coalesced to form the cores, after which the surrounding graphitic mantles were added by vapor deposition..." Kortoso (talk) 23:43, 29 September 2014 (UTC)
I see. Yes, there have to be several electron micrographs (TSM and STEM) available online. Cheers, BatteryIncluded (talk) 02:14, 30 September 2014 (UTC)
Here we are: A TRANSMISSION ELECTRON MICROSCOPY STUDY OF PRESOLAR HIBONITE [1]Kortoso (talk) 18:55, 9 September 2015 (UTC)

Isotopic pairing?Edit

"At the same time, L-excesses of alanine were again found in Murchison but now with enrichment in the isotope 15N,[2] however, the isotopic pairing was later contested on analytical grounds.[3]"

  1. ^ http://iopscience.iop.org/article/10.1088/0004-637X/730/2/83/meta
  2. ^ Engel, Michael H. (September 1, 1997). "Isotopic evidence for extraterrestrial non-racemic amino acids in the Murchison meteorite". Nature. 389 (6648): 265–268. Bibcode:1997Natur.389..265E. doi:10.1038/38460. PMID 9305838. Unknown parameter |coauthors= ignored (|author= suggested) (help)
  3. ^ Pizzarello, Sandra (1998). "Alanine enantiomers in the Murchison meteorite". Nature. 394: 236. doi:10.1038/28306. Unknown parameter |coauthors= ignored (|author= suggested) (help)

- this is an abstract from the article. The second part of the sentence says, "the isotopic pairing was later contested on analytical grounds." - was it? In the reference given after the statement I found only that they reported very similar δ15nitrogen values for L-alanine and D-alanine; these values are quite high in comparison with those of terrestrial amino acids. On this basis, they argued that contamination of the meteorite by terrestrial L-alanine can be ruled out because, if it contributed to the L-enantiomer excess, the lower 15N content of terrestrial L-alanine would significantly lower the δ15N value that they observed for L-alanine. So, not the isotopic pairing, but terrestrial origin of this pairing was contested. Or the terrestrial origin of l-alanine excess itself. Or have I misunderstood anything?-- Pyramid ion  14:03, 19 April 2014 (UTC)

ReferencesEdit

References 4 and 5 are given with the same author names. However, Ref. 4 in PNAS was authored by Y. Wolman, W.J. Haverland and S.L. Miller. Ricercatore (talk) 15:11, 19 October 2015 (UTC)

  Done, Thank you! -BatteryIncluded (talk) 16:11, 19 October 2015 (UTC)

External links modified (January 2018)Edit

Hello fellow Wikipedians,

I have just modified one external link on Murchison meteorite. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

As of February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{sourcecheck}} (last update: 15 July 2018).

  • If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
  • If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 23:22, 24 January 2018 (UTC)

Was the tremor "heard"?Edit

"About 30 seconds later, a tremor was heard." According to Dictionary.com, a sound is among the definitions of "tremor." It's my impression, though, that's a fairly obscure usage. Would it be correct here to say rather that the tremor was "felt"? The reference that follows doesn't detail the tremor so I'm unsure. — Preceding unsigned comment added by 24.29.63.96 (talk) 14:56, 14 January 2020 (UTC)

I have experienced earth tremors where there was definite;y something to be heard. I don't see a problem with the language. HiLo48 (talk) 17:30, 14 January 2020 (UTC)
10-4. Thanks. :-) — Preceding unsigned comment added by 2604:6000:1115:8612:D96E:B478:E5A0:C8CC (talk) 15:39, 16 January 2020 (UTC)
It seemed weird when I read it; I think it could be improved. Zaslav (talk) 00:16, 21 January 2020 (UTC)

Amino acids - ambiguous wordingEdit

The following phrase is problematic, because it tries to explain why amino acids are of interest, but can also be interpreted as suggesting the particular ones reported here are a result of life. This is not supported by the reference, which specifically reports these as "non-protein amino acids".

More than 15 amino acids, some of the basic components of life, have been identified during multiple studies of this meteorite.

I'd suggest the following:

Multiple studies of this meteorite have analysed for amino acids. More than fifteen different non-protein amino acid compounds have been identified in samples from this meteorite.

I have not checked for other references which may support the existing wording, so this is just a suggestion to authors who know the subject in greater detail. Wikiwayman (talk) 14:24, 16 January 2020 (UTC)

It is fair and correct to say that amino acids are some of the basic components of life. The 'Organic Compounds' section goes into much detail of what amino acids have been found and their analysis. I think the sentence to which you refer is just fine. CurlyMoeLarry (talk) 23:41, 18 January 2020 (UTC)

Nonprotein amino acids are not basic components of life. This seems misleading; it needs improvement. Zaslav (talk) 00:18, 21 January 2020 (UTC)

Semi-protected edit request on 19 January 2020Edit

To the citation that starts with <ref>{{cite journal |title=Extraterrestrial nucleobases in the Murchison meteorite ..., please at the following piece of code to enable wiki-links to Wikipedia articles for the paper's authors Zita Martins, Marilyn Fogel, and Pascale Ehrenfreund:

|author-link1=Zita Martins |author-link3=Marilyn Fogel |author-link9=Pascale Ehrenfreund

Adding the above author links would allow readers to find out more information about the authors of this scientific paper. 68.50.32.85 (talk) 01:39, 19 January 2020 (UTC)

  DoneThjarkur (talk) 11:24, 19 January 2020 (UTC)

Location(s) in collections?Edit

The article includes a photo of a sample of the meteorite in the National Museum of Natural History, Washington DC, but are other portions of the meteorite in other museums, or other collections, elsewhere in the world? It might be nice to include this information in the article. Cheers, LordAmeth (talk) 01:56, 20 January 2020 (UTC)

I know there are bits at the Melbourne Museum and at the University of Melbourne, (Melbourne being the capital and largest city in the state of Australia where Murchison is found), but it might be a bit hard to track down others. HiLo48 (talk) 02:08, 20 January 2020 (UTC)
Return to "Murchison meteorite" page.