From: Jo Butler <pjgb@mrc-lmb.cam.ac.uk>
  To  : o.byron@bio.gla.ac.uk
  Date: Thu, 18 Dec 97 17:16:16 +0000

Re: PEG

>Date: Thu, 18 Dec 1997 16:05:37 +0100
>To: rasmb@bbri.harvard.edu
>From: o.byron@bio.gla.ac.uk (Olwyn Byron)
>Subject: PEG
>
>
>Hello RASMBers
>
>I've got two quick questions to ask concerning polyethylene glycol (PEG).
>
>
>The second question concerns labelling PEG: does anyone know of an easy way
>to covalently (or non-covalently) label PEG (so that we can try AUC studies
>using absorbance optics)?
>
>Thanks in advance for your responses to these questions.
>All the very best for Christmas and the New Year-
>
>Olwyn Byron.
>
>
>_____________________________________________________________________
>Olwyn Byron
>Division of Infection and Immunity
>Institute of Biomedical and Life Sciences
>Joseph Black Building, University of Glasgow
>Glasgow, G12 8QQ, Scotland.
>
>tel: +44 (0)141 330 3752  email: o.byron@bio.gla.ac.uk
>fax: +44 (0)141 330 4600  web:   www.gla.ac.uk/Acad/IBLS/II/ob/ob.htm
>_____________________________________________________________________
>

Dear Olwen,

As an answer to your second question, I would point out that the only
reactive
groups on PEG are the hydroxyls at the ends, otherwise it is chemically a
poly-ether and not readily reactive.
You can label hydroxyl groups with many dyes, e.g. the Procion dyes, or
with a
fluorescent label.  The latter are not much use in the XLA, as there is
really
no room to include an emission filter between the cell and the scanning
slit and
also the geometry is awful for collecting the light.
The problem with a dye is that most of them (at least in the usual
visible
range) have extinction coefficients only in the range around 30,000 M-1
cm-1,
i.e. for Mr 100k one is looking for ~1mg/ml for an OD of 0.3.

I am currently looking into this question, for my own interest, and if I
find
anything much better, I will let you know.

With seasons greetings to all,

Jo Butler



-----------------------------
Jo Butler, 
MRC LMB,
Cambridge, UK.
Tel:+44 1223 248011
FAX:+44 1223 213556
Email: pjgb@mrc-lmb.cam.ac.uk
-----------------------------