recover a plasmid about 50kb with high yield? - (Nov/09/2001 )

I am trying to make the physical map of a plasmid from Lactococcus. SO I must get plenty of pure plasmid DNA.The plasmid is about 50kb in length and its copy number is very low. Considering our lab facilities,I can not use CsCl-gradient method to purify it. When I used the low temperature-melting agrose to recover it, I found the yield so disappionting.And many kits for purifying plasmid DNA limit the plasmd size below 5kb and so they are not fit for me. I wonder if there is another ideal way to purify my plasmid with satisfactory yield! Thank you for your attention and I am expecting advice!

Dear Sha Tang. I strongly recommend you the QIAGEN Plasmid purification protocols. Plasmids up to approximately 150 Kbp can be purified using this kits. You just have to choose the best for your conditions. There´s one specific for very low-copy plasmids/very low copy cosmids. You can get a yield up to 500 micrograms.I hope this has been useful for you.Best wishes; Carlos G. EstradaDpto ToxicologíaFacultad de VeterinariaUniversidad de León (España)