Talk:Arsenic biochemistry

People

Please stop confusing "arsenic-BASED" life with single cell life that can utilize arsenic, possibly as a replacement of phosphorous. It is WILDLY inaccurate to state that arsenic formed a successful part of the "genetic" makeup or functional DNA of the bacteria.

The hype should stop. Please go get an education. And stop editing the wiki. —Preceding unsigned comment added by 216.254.111.34 (talk) 19:59, 2 December 2010 (UTC)

I agree (mostly). This article is poorly titled (at least as far as it discussesGFAJ-1 rather than hypothetical extraterrestrial life-forms). GFAJ-1 isn't arsenic based. It's still carbon based. It uses arsenic instead of phosphorous in some circumstances, which is certainly a significant finding. Still, as with other terrestrial organisms, arsenic/phosphorous are a tiny chunk of the overall bulk of the organism. Maybe 0.5% of GFAJ-1 is arsenic (0.5% is roughly the amount of phosphorous in other organisms). 20% of GFAJ-1 is carbon, and the bulk of the remainder is water.192.104.39.2 (talk) 20:26, 2 December 2010 (UTC)

• I would have to say wait... Please refer yourselves [to this page here http://en.wikipedia.org/wiki/Talk:GFAJ-1]. The community consensus is to wait for a few days to see how the news plays out. Mrld (talk) 20:41, 2 December 2010 (UTC)

• Let's be clear. That consensus is only on merging of the two articles. Renaming this article, to a name more appropriate and in-line with the verifiable sources to date, need not wait for the merger discussion to be completed. See the next comment below. N2e (talk) 00:30, 3 December 2010 (UTC)

I think someone knowledgeable ought to consider making a proposal to RENAME the article. If so, it should be done in a new section (below) on this Talk page. I would be inclined to support such a rename as there certainly doesn't seem to be reliable source verifiability for the claim implied by the current article title (Arsenic-based life). N2e (talk) 00:28, 3 December 2010 (UTC)

If the phrase "arsenic based life" is being used, its incorrect. I would recommend we let the scientific community come up with a name, which may be more like "arsenate substituted nucleic biology". arsenic based life is a phrasing equivalent to "carbon based life" which of course this org. is. we really dont need to ADD to the dumbing down of the population. Until we get a good name, i think a neutral term like "arsenic in biological processes" would work better. not as glamorous of course.Mercurywoodrose (talk) 02:50, 3 December 2010 (UTC)

"Arsenic DNA" is a misnomer, people. It's nonsensical. It is wildly misleading, although it slightly less foolish than "Arsenic-based life" (in reference to the bacterial sensation). Phosphorous has a molecular role in the backbone of DNA, not the codons, and even then, the concentration of phosphorous in DNA is the lowest, by far, of all other constituent elements. Just look at a DNA diagram. The term "Arsenic DNA" is like calling your vehicle a "Rubber Car!" because your tires are rubber. This is moronic, and goes back to highly irresponsible journalism by "New Scientist", and it's now getting entrenched on wikipedia by people who don't know what they're talking about, although they are very excited to talk about it.

And even then, we're still not talking about an entire genome with P in place of As, because the bacteria merely showed a higher-than-normal levels of Arsenic and lower-than-normal levels of Phosphorous in some tests, after the environment was saturated with arsenic. One test supposedly indicated that Arsenic had taken on the molecular role of phosphorous in the backbone, but the title of this article is still nonsensical. 216.254.111.34 (talk) 18:33, 3 December 2010 (UTC)

Article title proposals

Let's started a list of proposals for renaming this article:

• Arsenic-accommodating organisms. This is my first proposal. --Thorwald (talk) 05:08, 3 December 2010 (UTC)

My proposal is

• Arsenic-DNA hoax

This is going to be a new Sokal affair

http://en.wikipedia.org/wiki/Sokal_affair

Alfredr (talk) 14:16, 3 December 2010 (UTC)

The "hoax" proposal is hilarious, and much more accurate than "Arsenic DNA" in my view. But still, I'd suggest something like

• Arsonate-Phosphate Substition in DNA (I am not a chemist)

or

• Arsenic-Phosphorous substitution in DNA.

• Arsenic-laced life, from a commentator at the Wired.com article. Highly accurate, and also hilarious.

• Arsenic-accommodating life is great, because the focus needs to be moved away from DNA. Preferably far, far away. There's no evidence that the DNA had a purely arsonate backbone, nor that a stable lineage would ever be viable from such a thing.

You don't need to be an expert in the field to see through the stupidity surrounding the issue. I encourage everyone to look at a DNA diagram, and notice that there are very few "P's", and that they occur only on the non-coding side-lines of the codon ladder. Even still, it's beside the point, because the Arsenic supposedly was taking a role outside the DNA as well. Yawn. Wake me up when we get a probe on Titan.216.254.111.34 (talk) 20:21, 3 December 2010 (UTC)

This page was renamed from Arsenic-based life to Arsenic DNA by a banned user. I have removed all of their other changes, but given that the name is being discussed here, I wont restore it to the previous name. Hopefully someone more knowledgeable can opine on whether this name is appropriate or provide a better name. John Vandenberg ^(chat) 03:20, 4 December 2010 (UTC)

On the name

Okay, I get why "arsenic-based life" is a bad name. It was both misleading and arguably wrong. On the other hand, it had the virtue of being widely used in the popular press (though not by scientists, as far as I could tell). I'm not sure where the name "arsenic DNA" came from but it seems to be almost a novel invention. Very few accounts seem to have adopted that compound noun, and I'm not sure any of those accounts use it to refer to both the DNA with arsenic in it and more generally to the ability to incorporate arsenic in other biomolecules, as this article currently tries to.

So, I don't think "arsenic DNA" is a good name either. Perhaps we need to settle on something longer and more descriptive? "Phosphorus replacement by arsenic", "Microbial arsenic substitution", "Arsenic-based biomolecules". Frankly, I don't know what the right title is, but I don't think that "arsenic DNA" is it. Dragons flight (talk) 11:17, 3 December 2010 (UTC)

I agree with the above. From what I gather, we are still awaiting further research to confirm in what compounds GFAJ-1 incorporates arsenic. However, it's probably more than just DNA. ATP (ATAs?), isn't considered DNA, is it (even though it contains a nucleotide)? I'm not sure where all phosphorous shows up biochemically; predominantly in DNA for sure, but there are other compounds floating around as well. The titles proposed by Dragons flight above seem decent, but we should probably wait until an appropriate term appears in the scientific literature.192.104.39.2 (talk) 16:28, 3 December 2010 (UTC)

I think the article needs expansion. The current article is solely about the new organism announced by NASA. But according to our own arsenic article, there are microbes that use arsenic in photosynthesis where arsenate replaces water. That should also be in this article. With that expansion, we can come up with a better name. "Arsenic DNA" is definitely bad, since even with the current article contents, it covers more than having arsenic in DNA. Arsenic in other biomolecules is already covered here. 65.93.12.108 (talk) 11:30, 3 December 2010 (UTC)

"Arsenic DNA" is a misnomer, plain and simple. It's nonsensical. It is wildly misleading, although it slightly less foolish than "Arsenic-based life" (in reference to the bacterial sensation). Phosphorous has a molecular role in the backbone of DNA, not the codons, and even then, the concentration of phosphorous in the DNA [backbone] is the lowest, by far, of all other constituent elements. Just look at a DNA diagram. The term "Arsenic DNA" is like calling your vehicle a "Rubber Car!" because your tires are rubber. (The moronic trend probably started with the "New Scientist" in 2008.)

Furthermore, we're still not talking about an entire genome with P in place of As, because the bacteria merely showed a higher-than-normal levels of Arsenic and lower-than-normal levels of Phosphorous in some tests, after the environment was saturated with arsenic. One test supposedly indicated that Arsenic had taken on the molecular role of Phosphorous in the backbone. Even if the evidence was perfect that arsenic could fully replace phosphorous in the genome, "Arsenic DNA" would still be a terrible name. 216.254.111.34 (talk) 18:33, 3 December 2010 (UTC) —Preceding unsigned comment added by 216.254.111.34 (talk)

expansion

This article is too focused on the new NASA organism. It should be expanded to cover the theoretical aspects of arsenic in life, substituting for some other chemical that most life uses instead. It should also cover other organisms. The arsenic article already mentions the use of arsenate in replacement of water for photosynthesis for Ectothiorhodospira shaposhnikovii.

Theoretical biology and astrobiology aspects need to be increased.

65.93.12.108 (talk) 11:35, 3 December 2010 (UTC)

Chemistry of arsenates

From the article: "One of the reasons this result is unexpected is because arsenate is generally unstable in water, with a half-life measured in minutes." Does this mean something like, "Chemical bonds between carbon atoms and arsenate groups are generally unstable in water"? Can someone cite some references? --JWSchmidt (talk) 01:27, 3 December 2010 (UTC)

From the journal article: "AsO4 esters are predicted to be orders of magnitude less stable than PO4 esters, at least for simple molecules". The line you quote is based on the press conference (possibly somewhat garbled) where one of the panelists indicated that he had expected arsenate based DNA would be unstable and break down with a half-life "like 10 minutes". Dragons flight (talk) 01:47, 3 December 2010 (UTC)

There are interesting hits on http://www.google.com/#q=arsenate+hydrolysis but if DNA is the main focus then you might consider it a mismatch.

• Synthesis and Hydrolysis of ADP-Arsenate by Beef Heart Submitochondrial Particles] THE JOURNAL OF BIOLOGICAL CHEMISTRY Vol. 258, No. 10. Issue of May 25, pp. 6266-6271, 1983
  • "The first order rate constant for ADP-arsenate hydrolysis at pH 7.5, 30 C, was determined to be greater than 5 min-1 and was estimated to be 70 min-1."
• Kinetics of the hydrolysis of arsenate(V) triesters Inorg. Chem., (March) 1981, 20 (3), pp 905–907 doi:10.1021/ic50217a052
  • "The hydrolysis of trimethyl arsenate in methanol solution was first order in ester and in water with k1(25C) = 73 M-1 s-1, delta enthalpy of 13 +/- 1 kJ mol-1 and delta entropy of -167 +/- 13 J mol-1 K-1. Hydrolysis rates of the esters decreased in the order methyl > ethyl > n-pentyl > isopropyl. An associative mechanism is proposed."

Again, nothing yet with DNA.--Sharonmil (talk) 03:31, 3 December 2010 (UTC)

Doesn't this rate of decay depend very heavily on the pH? Abductive (reasoning) 11:22, 3 December 2010 (UTC)

Right! Most of the hydrolysis is either base or acid catalysed.--13:24, 3 December 2010 (UTC)

There's criticism suggesting it may had been a false announcement.

http://www.space.com/scienceastronomy/arsenic-bacteria-alien-life-101202.html --Leladax (talk) 19:30, 3 December 2010 (UTC)