Deng/Nickoloff mutagenesis

[Scott Vande Pol]

We have been making site specific mutations by the Deng/Nickoloff technique
(aka clontechs "altered sites" kit or stratagenes "chameleon" kit) .  We
have had some undesired frameshift mutations at the ends of the
mutagenizing oligos, but have not yet found second site undesired
mutations.  Although T4 polymerase has a very low polymerase error rate,
other factors (methylation of the nucleotides, passage through  mutS
bacterial strains, etc ) may effect second site mutation rates.  Does
anyone know of any data ( or have personal experience) on the frequency of
undesired second site mutations using this procedure? 
	Thanks for any info on this!

-- 
Scott Vande Pol
Case Western Reserve University
Department of Pathology
Cleveland Oh. 44106
sbv at pop.cwru.edu