MOPS BUFFER- Need ADVICE

[Bernard Murray, PhD]

In article <38317392.A5C5D0C2 at uni-konstanz.de>,
Frank.Fackelmayer at uni-konstanz.de wrote:

> "Bernard Murray, PhD" wrote:
> 
> > In article <3830525A.A98B327C at unix.ccc.nottingham.ac.uk>, james stevenson
> > <pcxjs at unix.ccc.nottingham.ac.uk> wrote:
> >
> > > If its gone yellow, then its decomposed.
> >
> > This is nonsense.  Clear straw-yellow MOPS solutions are just fine
> > (I consider it a helpful indication that it has been autoclaved
> > - although MOPS buffer will turn yellow spontaneously on exposure
> > to air).
> 
> I don´t think it is nonsense to say that the yellow color of MOPS results from
> its decomposition.

Sorry, the original context was that the "decomposed" buffer was unusable
and that was the point I was disputing.  I agree that something must have
changed if the colour is different.  It still acts as a buffer and has
no detrimental effect upon RNA.

> That said, I have to admit that I once used autoclaved MOPS after 2 years on
> the shelf at RT (dark yellow!), and had no problems at all. Apparently
> decomposition only affects a small proportion of the stuff and there is enough
> intact MOPS left....

That was exactly my point.  You can buy commercial MOPS solutions
and all the suppliers I have seen autoclave their offerings so
the solutions are yellow.  I've used solutions several years old
without any problems (stored room temperature out of direct sunlight).

   Bernard

-- 
Bernard P. Murray, PhD
bpmurray at cgl . ucsf . edu
Department of Cellular & Molecular Pharmacology, UCSF