71450.1773@compuserve.com (Steven B. Harris) (12/05/90)
>Assuming you knew where to look, normal radioactive decay of
an individual atom is a comparatively tame event, compared to
fission of an atom. I can't say whether it would be energetic
enough to break DNA bonds. Anybody know?<
My comment: 32P decays by emitting a pretty hot beta at 1.71
Mev. By conservation of momentum (relativistic momentum for the
electron at these energies, remember!), one can calculate that
the parent nuclide recoils with an energy of about 79 electron
volts. That's more than enough to break any chemical bond (a few
ev) and send the atom (now a sulfur nucleus) screaming off into
the distance at Mach 65 or so. So don't blink when you're
watching through that old STM, boys.
As to your chance of "seeing" this happen under an STM, it's
pretty good. I once calculated the theoretical specific activity
of 100% 32P labeled nucleotide, and found that you can get stuff
delivered to your door from New England Nuclear with better than
50% theoretical activity (that means they must start with nearly
100% isotopic purity down there when they make the stuff--
bravo). Theoretically, then, you could stick such a nucleoside
residue enzymatically at the end of a DNA chain, and watch it for
a week or two till it popped.
I have to admit that I can't see exactly why the idea of doing
this gives everybody the shivers, though. It isn't like you'd be
peaking at the secret mechanisms of God; instead the thing would
just vanish like a pricked soap bubble. Big deal. That happens
under STMs to lots of things everyday as it is.
Steve Harris
P.S. This is my first message on INTERNET. Hope it comes out
okay.