Rebase

Yep, rebase is a good site ! I used it for my biology olympiad exam.

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One of the most complete I know: http://rebase.neb.com/rebase/rebase.html

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According to this site: http://rebase.neb.com/rebase/enz/XbaI.html XbaI is methylation sensitive. I am not familiar with mouse methylation systems but it might be a cause of your problem? Otherwise I don't have any idea.

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... cut it. This recognition can be affected by methylation of the DNA molecule. If you want a list of restriction sites, you can use thi site: http://rebase.neb.com/rebase/rebase.html

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Try a short cutter (usually 4 are used like RsaI the fragments are in the few hundreds base long) or something with lots of N. Have a look on rebase . But <200 base, that is really small.

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