TOPO cloning kits from invitrogene

Frank Lee sw12345 at
Thu Oct 21 01:31:03 EST 1999

Hi, everyone:

I know there are some discussion abuot TOPO cloning kits from
invitrogene. I have a similar problem recently. I inserted a 211 bp
fragment into their plamsid following procedure and checked 4 clones. 3
of them are correct. However, the last one is much bigger. When I cut it
with Xho, the size of this linearized plasmid is about 10kb. The correct
size should be 3.7kb only. The interesting thing is that it gave me
correct pattern when I cut it with EcoRI. It showed the linearized
plasmid at 3.5kb and insertion fragment at 200 bp. Does anyone have a
similar problem before? I think the TOPO cloning kits is great and very
convienent. However, it seems that the topoisomerase I is wierd
sometime. If anyone has any idea about this, please let me know.


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