could cutting with enzyme EcoR I give a blunt end?

Answer 1

It shouldn't--it isn't a blunt cutter. The only way to get a blunt end fragment after an EcoRI digest is if you do a gap filling reaction or if there is some nuclease activity present that is degrading the ends.

EcoRI itself does not possess any nuclease activity--according to the New England Biolabs website, after overdigestion with EcoRI, "> 95% of the DNA fragments can be ligated with T4 DNA Ligase (at a 5' termini concentration of 1-2 μM) at 16ºC. Of these ligated fragments, > 95% can be recut with EcoRI."

If you are having trouble with EcoRI, you can contact the company (e.g. New England Biolabs) and obtain additional help.

Answer 2

No. EcoR1 produces a staggered cut, and thus sticky ends. Here is a list of restriction endonucleases from one company. If you click on any of the enzymes, you can find out what sequences the enzyme recognizes, and how it cuts that sequence.

http://www.neb.com/nebecomm/products/category1.asp

(Note: I have no relationship with this company. I just googled and found it.)

Answer 3

nope