Q] Circular DNA size determination

[Hyunmin Kim]

I have delt with circular Plasmid(4kb).
It has 2 site for SalI between 300bp distance.

I digested this plasmid with SalI, and I self ligated this plasmid.
Then  I will have a plasmid with 300bp deleted(=3.7kb).

To distinguish whether  a certain plasmid is 3.7kb or 4.0kb, Do I must
linearize the plasmid with appropriate restriction enzyme?

If both 3.7kb and 4.0kb circular plasmid is applied to
electrophoresis(with no Resctiriction enzyme added), There is no way to
distinguish 3.7, and 4.0kb ?

I would like to know if there is any method to distinguish 2 different
size Circular DNAs without linearzing the DNAs(no restricion enzyme
added.)

(Because it is uncomfortable, and enzymes cost much.)


--
Hyunmin Kim
Laboratory of Microbiology
Department of Biology
College of Natural Science
Hanyang Univ.
Haengdang-dong 17                Fax   : 082-02-290-0952
Seoul, South Korea               E-mail: vurk at hymail.hanyang.ac.kr

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