From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Thu Aug 29 2002 - 11:07:38 MDT
On Thu, 29 Aug 2002, Anders Sandberg wrote:
[snip]
> The big limiting factor of tunneling is usually
> the exponential effect of the barrier width. I guess (handwaving alert)
> that this is a few Å for the deamidation scenario, and the mass involved
> is at least a hydrogen atom. That sounds like a very low rate.
Actually, it seems to depend a lot on the local atomic environment for
the asparagine and glutamine amino acids and the time frame seems
to range from days to a year or two. I don't think I would call that
a tunneling effect, but am unsure what I would call it.
> Personally I would start to worry about this after I got rid of the K40,
> C14 and P32 in my body.
I think the deamidation reactions take place at a rate that greatly exceeds
damage caused by radioactive decay.
> Cool! Could this be used for dating archeological finds?
Perhaps, but the time curves I've seen (see the papers by Robinson et al)
seem to suggest that the time frames for these reactions (at body temps)
are measured in days to a year or two. So I'd guess C14 and K40 have
much greater use for dating purposes than deamidation. Their algorithm
also seems to require the full 3D atomic environment and that presumably
isn't available in most archeological circumstances.
Robert
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