Methods Digest, Vol 19, Issue 21: A REQUEST (meenakshimalik malik)

[Jess]

Hi Malik,
   
  Is your plasmid REALLY 30.5 kb??? That's a pretty big plasmid. The Qiaex II kit can extract plasmid DNA up to 50 kb. Link to the kit info is below.
   
  http://www1.qiagen.com/products/dnacleanup/qiaexiigelextractionsystem/qiaexiigelextractionkit.aspx?ShowInfo=1
   
  I and others have used this kit for extraction of very small and very large DNA plasmids and fragments before and we have found it to be a good product. Please note in the Qiaex II kit there are protocol modifications that must be carried out to ensure good recovery of the large DNA fragment. What protocol are you using now? Is this the same kit you are using, or are you using the modified Wizard prep protocol (kit from promega)? 
   
  Is it possible that your plasmid is not recovered because it is not present? I gather from your message that you are seeing your band on the gel, but just can't get it out of the agarose. If this is the case- try heating your gel to 60-65 degrees C, then proceed according to the kit instructions for DNA fragment your size. This often helps in cases of low extraction, even with normal sized plasmids/ DNA frags. 
   
  Cheers and Good wishes for the Holiday Season,
  Jess
   
  Grad. Res. Asst.
  University of Texas - Austin
  Department of Medicinal Chemistry
  Hook 'em Horns!
   
  Message: 2
Date: Thu, 21 Dec 2006 15:08:36 +0000 (GMT)
From: meenakshimalik malik 
Subject: A REQUEST

Dear sir,
i have a problem for eluting a plasmid DNA of 30.5kb from the agarose gel.I have even used kit for the purpose but its not giving the appropriate results.
Plz help me to come over this problem by helping me to get a method for its elution.
thanking u



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