[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: H. C. Urey's work



Robert S Verish wrote:

>      Hello Martin and Joseph,
>
>      Interesting posts.  Can you give me some more information regarding this
>      "L-isomer biase", and its relationship to amino acids from living
>      organisms?  I think this topic is related to this recent finding:

>     Hello Robert, Joseph and List,
>
> I hope more articles of this nature can be found and posted. I know there is at
> least one other floating around out there, but I have been unable to find it.

> For those on the List who are a little confused by the talk of an L-bias,
> asymmetry  in organic molecules, or in case you slept through you high school
> biochem classes, stereochemistry is the study of similar but not identical
> chemical compounds. The issue is that the compounds differ only in that they are
> mirror images of each other. When compounds form, the electron sharing will work
> as a swivel allowing the molecule to change shape by rotating around the electron
> bonds. If double or triple bonds are inplay, it is not possible for the different
> parts of the molecule to rotate.
>
> Since the bonds can occur in different but stable positions, there can be
> different versions of what is essentially the same molecule. These molecular
> mirror images of each other are known as right and left-handed molecules, or L
> and D isomers. You can invision a pair of gloves; essentially they are identical,
> except they are mirror images of each other.
>
> Life, as we know it uses only the L or left-handed amino acids. However, the D
> and L versions of amino acids exist in roughly equal portions in nature. The
> significance of the preponderance of L or left-handed amino acids in Murchison
> indicates that some other process may be in play other than the normal
> ‘randomness’ of nature.
>
> My statement to Joseph and the List of: "It seems the L-isomer bias may be a
> fingerprint for life as we know it. Or maybe, life is as we know it." Is my
> feeling that the preponderance of L amino acids in an environ may be a possible
> indicator of life or past life. To take this a step further, life as we know it
> may, at least chemically, be similar regardless of the location in the solar
> system, or even the universe for that matter.
>
> Now, to hopefully head off the shoveling of criticism upon the implications and
> generalizations of the above statement, I am fully aware of both the limitations
> of the current knowledge in the area, as well as the grand chasm I just crossed
> without the use of science as my bridge. My point is simply to share what is, and
> what could be. Not to offer them as equivalents.

On a side note, a friend of mine was one of Urey’s graduate students who also did
research on meteorites. Eventually, he had what he believed was overwhelming
evidence that Urey’s conclusions about the origin of meteorites was wrong. He and a
colleague published their findings going directly against Urey. If you want to know
more, you can read about it Cosmic Debris by Burke.

I also did my undergraduate work at the University of Montana where Urey also did
his undergraduate work decades earlier. I even went to chemistry classes in the
Urey Lecture Hall.
     Cheers,

> Martin
>
>
>







































----------
Archives located at:
http://www.meteoritecentral.com/list_best.html

For help, FAQ's and sub. info. visit:
http://www.meteoritecentral.com/mailing_list.html
----------
References: