restriction endonucleases and ss DNA or DNA/RNA hybrids

Tue Aug 6 14:07:00 EST 1991

Regarding the question:

>does anyone know of a source for information concerning the sensitivity
>of DNA to cleavage by restriction endonucleases when the DNA is single
>stranded or when it is found in an RNA/DNA hybrid.  The only source
>I have currently is the NEB catalog p.135 (1990).  Thanks.

A number of years ago we did a series of experiments where we asked a
similar question.  As controls we used ds-pUC and investigated restriction
endonuclease cleavage of ss-m13mp7 by over 50 different restriction enzymes
as a function of temperature.  (m13mp7 has a polylinker with a 2-fold symmetry)

Our results, which were never published, were consistent with the hypothesis
that cleavage occurred *ONLY* when the ss DNA formed a ds region, because the
cleavage of ssDNA could not be observed when the temperature was raised to melt
the ds regions and the enzymes were still active at the elevated temperature
as demonstrated by the pUC cleavage control.

Hope this is helpful.

 \  Bruce A. Roe                    INTERNET: BROE at  /
 /  Dept. of Chem. and Biochem.     BITNET:   BROE at uokucsvx                 \
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