PEG and ligation

[Bill Melchior]

Regarding the use of ligation accelerators like PEG or hexamminecobalt,
one thing about them that has always worried me is statements like the 
following from Sambrook et al (page 1.70 of the second edition of 
Molecular Cloning):

"They alter the distribution of ligation products.  Intramolecular ligation 
is suppressed, and the ligation products are created exclusively by 
intermolecular joining events.  Thus ... all the DNA products are linear 
multimers."

I assume this can't literally be true, or the transformation efficiency of 
the ligation products would be very low, but I'd be interested in comments 
on this aspect.  For instance, if I want to put a blunted insert of a few 
hundred bp into a plasmid of 4-5,000 bp, would I be better of using PEG or 
HAC, or not?

________________________________________________________________________________
Views expressed are not necessarily those of NCTR, its sponsoring agencies,
or the United States government.

Bill Melchior                                ||    
National Center for Toxicological Research   ||    ALL statements
Jefferson, AR  72079                         ||    in this
(501) 543-7206                               ||    signature box
                                             ||    are false.
WMELCHIOR at NTET.NCTR.FDA.GOV                  ||