What happens to 32P-labelled compounds?

Bruce Roe broe at aardvark.ucs.uoknor.edu
Fri Jul 31 06:46:00 EST 1992


In article <3660 at fcs280s.ncifcrf.gov>, toms at fcs260c2.ncifcrf.gov (Tom Schneider) writes...
>In article <1992Jul30.085812.18345 at polaris.utu.fi>
>eepee at polaris.utu.fi (Esa-Pekka P{lvim{ki) writes:

	<stuff deleted>

>An interesting question on these lines is:
> 
>Suppose one labeled some DNA with 32P.  Then look under an STM.  Watch again.
>Watch again.   POOF!  Look again and there is a little crater there or what?
>This experiment is easy to do and one would be (I think) the first person
>to observe the radioactive decay of a single molecule.  If someone does
>the experiment I'd like to know the result.  (I ran some calculations on this
>a while back, and it seems like one would not need to wait very long to see
>some molecules decay if one watched a large enough set of them.  Half life
>of 32P is only 2 weeks.)

IMHO you would see a 32S where there once was a 32P but *no crater*.
Lest we forget, the radiolabeled molecules we use as "tracers" usually
contain a very large excess of non-radiolabeled carrier and the actual
number of molecules which decay in the population is quite small compared
to those that do.  BTW, 32S is a stable isotope of sulfur so there would
be no further decay of those atoms.

A simplier experiment than Toms, would be to lable a batch of DNA with
alpha-32P-dATP and then run a series of gels (say 1 every other day)
and look to see if the DNA falls appart in time as the 32P goes to 32S.
My guess is if the tube were not contaminated with nucleases you'd not
see any degredation.

;-)

Cheers -- bruce
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 \  Bruce A. Roe                     Dept. Chemistry and Biochemistry /
 /  BROE at aardvark.ucs.uoknor.edu     University of Oklahoma           \
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