realistic life of 35S methionine for protein labelling

[Chris H Lindley]

Hi all,


What would you say is the realistic life of 35S Methionine fore in vitro
expression labelling of proteins?

i.e. after 3months (halflife) does just the radioactivity become
half (i.e. just double the exposure time) or are there other
factors that need to be taken into account!

I ask this as increasing the exposure to get a decent image on a
SDS-PAGE I've just done in order to get a decent image, results
in porr definition of bands and a very high background.
Which isn;t apparent from coomassie staining of the gel!

The Methionine is just 3 months old! Am I being too
cheap in not using some fresh stuff:-)


Cheers
Chris




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ATGCTGCTAGTCGTAGCATGCTGCTTGATCGATGCGGTACGTGATGATCGTAGCTAGCTGGGCTAGTGG
¦  Chris H. Lindley                                  Yorkshire, UK  ¦
¦  chris at scotgate2.demon.co.uk     Ferg on #os/2 and #os2uk, EFnet  ¦
¦  WarpUK:UK OS/2 Users group                   www.warp.in-uk.net  ¦
¦  Molecular Biology & OS/2               www.scotgate.demon.co.uk  ¦
TACGACGATCAGCATCGTACGACGAACTAGCTACGCCATGCACTACTAGCATCGATCGACCCGATCACC