B-galactosidase negative selection - B-thio-o-nitrophenylgalactoside (TONPG)

Emir Khatipov khatipovNO at NOuchicago.edu
Wed Apr 24 18:18:33 EST 2002

Some chemicals Sigma sells are not made by Sigma. You might want to ask them
again if they know who was their supplier.
you may also try http://www.biosupplynet.com/index.cfm and search for
"galacto" as I just did. Seems to be lots of relevant references. Hope this

""Haigh, Dr R.D."" <rxh at leicester.ac.uk> wrote in message
news:DC88BEDFD1FC3F468D0376A7C75465F755AC04 at saffron.cfs.le.ac.uk...


I'm trying to find a source for b-thio-o-nitrophenylgalactoside (TONPG)
which is used as a negative selection for B-galactosidase expressing
bacteria. The last paper I can find that used it was in 2000 and cites their
source as Sigma - unfortunately this must have been an old lab stock as
Sigma have not sold TONPG for some years. Does anyone know of a supplier
currently selling TONPG ?




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