Two questions: Absolute EtOH and Carboxypeptidase Digestion
jhaines at uoguelph.ca
Sun May 27 14:42:35 EST 2001
Hi, I know this is a molbio board, but I'm going to post my chem
question anyways since I know there are a lot of helpful people on this board.
I recently performed an experiment involving the determination if an
equilibrium constant in two solvent systems: (1) absolute ethanol and
(2) water I am writing up my report, and I'm trying to compile a list
of errors that may have caused a deviation from the experimental value.
The reaction mixtures were left in the open for 20 minutes before
titration. Anyways to cut to the chase... Two explanations I would like
to give for possible erros are: (a) ethanol evaporated from the beaker
before the titration was performed and (b) the stock solution of
'absolute ethanol' absorbed water from the air making it not a pure
"solvent system" -- would anyone know what %age the EtOH would be after
absorbing water? (ie. ?95%?, 90%?)
Also, does anyone know how to remove a His tag from the C-terminus of a
protein after Ni-affinity chrom. purification -- would
the trick? or are there other enzymes that would do this?
Thanks in advance for responses and for reading the post!
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