Methylation-sensitive Isoschizomers Hpa II / Msp I Strange Results

Dr. Duncan Clark duncan at
Thu May 22 03:07:25 EST 1997

In article <32253b24.408270 at>, Russ Watkins
<watkins at> writes
>The results I get are complete digestion
>with Hpa II and no digestion at all with Msp I.  There's no
>combination in the table above to explain this result.  What's even
>more puzzling to me is that I get the same kind of reversed results
>for Cfo I / Hha I digestions.  

I've never heard of differences in methylation between Cfo and Hha. Can
you be sure that the enzymes are OK or that you haven't got some
contaminant in with your DNA that is stopping one of the isochizomers
cutting. Try adding a known cuttable plasmid or phage DNA to your xsomal
digest. If there is no inhibitor present the plasmid should be cut by
all enzymes. 

The problem with being on the cutting edge is that you occasionally get 
sliced from time to time....

Duncan Clark
DNAmp Ltd.
TEl/FAX 01252376288

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