Has anyone cut pCH110 (the famous lacZ plasmid) with ClaI?

Michiaki Masuda masuda at fcs110c.ncifcrf.gov
Wed Dec 22 20:27:15 EST 1993

   I'm using a lacZ gene-containing plasmid, pCH110. According to the
nucleotide sequence, there are two ClaI sites within the lacZ gene.
However, when I cut the DNA with ClaI, I get only one fragment corresponding
to the full-length plasmid.

   Yes, you guessed it. The sequence around one of the two ClaI sites
matches the _dam_ methylation site. (My DNA was propagated in DH5a.)

   My question is:

   Can I convince myself that the unexpected restriction pattern is due to
the methylation?

   If there is anyone on the net who has digested pCH110 with ClaI, I'd
appreciate it if you could tell me your result.

   Thank you.


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