UNIT 10.5 Isolation and Purification of Large DNA Restriction Fragments from Agarose Gels

  1. David Moore1,
  2. Joanne Chory2,
  3. Randall K. Ribaudo (NA-45 paper)3

Published Online: 1 MAY 2001

DOI: 10.1002/0471142735.im1005s08

Current Protocols in Immunology

Current Protocols in Immunology

How to Cite

Moore, D., Chory, J. and Ribaudo, R. K. 2001. Isolation and Purification of Large DNA Restriction Fragments from Agarose Gels. Current Protocols in Immunology. 8:II:10.5:10.5.1–10.5.12.

Author Information

  1. 1

    Massachusetts General Hospital, Boston, Massachusetts

  2. 2

    The Salk Institute, La Jolla, California

  3. 3

    National Institute of Allergy and Infectious Diseases, Bethesda, Maryland

Publication History

  1. Published Online: 1 MAY 2001
  2. Published Print: DEC 1993


This unit describes methods for recovering and purifying DNA restriction fragments from agarose gels. The first basic protocol describes electroelution of the fragment of interest from standard agarose gels using buffer-filled dialysis bags, followed by concentration and purification using an Elutip column. This approach can be used effectively for fragments of all sizes from 50 to 20,000 bp. Electrophoresis directly onto NA-45 paper is also described and provides relatively high yields for fragments smaller than 2000 bp. Protocols are also provided for separating fragments larger than 1000 bp using low gelling/melting agarose gels and purified by phenol extraction, b-agarase digestion of the gel, or via glass beads extraction. Sieving agarose gels can also be used to resolve very small DNA fragments. Removing linkers from a fragment using a column rather than a gel is included, followed by a method for estimating DNA concentrations in solution.