Specificity of DNAase I?

David Johnstondaj daj at uk.ac.ic.nhm
Wed Oct 13 05:46:48 EST 1993


On 12 Oct 1993 08:57:51 GMT,
  horst ibelgaufts writes:

>Is DNAase I strictly double-strand specific? If not, what are the
>conditions for attacking also single strands of DNA?
>Thanks

according to "Molecular Biology Labfax" (edit T. A. Brown, Blackwell 
Sci. Pub. Ltd., ISBN 1 872748 00 7 - check it out, its invaluable for this 
kind of thing)

degrades ss and ds DNA by cutting preferentially 5@ to pyrimidines 
resulting in mono and oligo nucleotides with an average length of 4 nt.


Requires Mg++ but this can be replaced by Mn++ to cause double stranded 
breaks

use @ 37C

Some suppliers recommend adding 20 mM CaCl2 to mix

10X buffer: 500 mM Tris-HCl (pH 7.5), 10 mM MgCl2, 1mg/ml BSA

Cheers,
DAJ
David A. Johnston
Dept of Zoology, The Natural History Museum, Cromwell Road,
South Kensington, London SW7 5DB.
(tel 071 9389297, fax 071 9388754, email daj at nhm.ic.ac.uk)



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