PEG in ligations

[Zophonias O. Jonsson]

In article <4pji3m$olk at scotsman.ed.ac.uk>, chrisb at hgu.mrc.ac.uk (Chris
Boyd) wrote:

> That's interesting.  I have found that the presence of PEG at and
> somewhat above the levels one uses in ligation makes no difference to
> transformation (by electroporation) frequencies.  

I have seen this legend as well several times but always hesitated to
believe.  Just check the 2xTSS (Trasformation Storage Solution) from
Current Protocols page 1.85.  It contains 20%  PEG 3350 and is used to
make competent cells.  This method reproducibly gives competent E. coli of
tolerable quality.  I have even used cells treated this way to construct a
library.  If PEG can be included in a solution to make competent cells at
this concentration, how can a bit of PEG in a ligation be expected to
inhibit transformation ?  Does someone have some relevant data to prove
the point ?

Zophonias

_____________________________________________________________________
Zophonias O. Jonsson
Institut fur Veterinarbiochemie               Tel: (41-1)-257-54-75
Universitat Zurich-Irchel                     Fax: (41-1)-362-05-01
Winterthurerstrasse 190
CH-8057 Zurich
Switzerland
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