Two questions: Absolute EtOH and Carboxypeptidase Digestion

[Henk Veldman]

Michael Witty schreef:

> > 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.
>
> We are flattered!  Though my chemistry is very weak.
>
> > I recently performed an experiment involving the determination if an
> > equilibrium constant in two solvent systems:  (1) absolute ethanol and
> > (2) water
>
> What is your system?  A peptidase reaction in water (buffer?) and ethanol
> (buffered ethanol?)
>
> > would anyone know what %age the EtOH would be after absorbing water?
> > (ie. ?95%?, 90%?)
>
> No, not off hand but I think the keyword is azeotrope.  Ethanol cannot be
> made 100% by distillation and has a tendency to keep a certain amount of
> water.  Try checking a chemistry textbook for ethanol distillation (or
> look at the data printed on the side of the ethanol bottle).
>

The azeotrope contains 95.57 % ethanol by weight (according to The Merck Index).

Henk




--
H. Veldman
Laboratory for Experimental Neurology (NMZ)
University Medical Center Utrecht (AZU)