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  • DNA Purification


    β-Agarase I can be used to purify both large (>50 kb) and small (<50 kb) fragments of DNA from gels, and the resulting carbohydrates can be removed if necessary.


    Large DNA Fragments:Fragments larger than 50 kb require delicate handling to avoid mechanical shearing, so we advise that subsequent manipulation be carried out in the digested agarose or that a drop dialysis step be introduced to remove carbohydrates and β-Agarase I (MW 30,000).

    Small DNA Fragments:Alcohol precipitation of DNA (carbohydrates remain in solution).


    1. Adjust the salt concentration of the β-Agarase I treated solution for isopropanol precipitation of DNA (0.5 M NaCl, 0.3 M NaOAc, 2.5 M NH4OAc or 0.8 M LiCl).
    2. Chill on ice for 15 minutes.
    3. Centrifuge at 15,000 X g for 15 minutes to pellet any remaining undigested carbohydrates.
    4. Remove the DNA-containing supernatant. Precipitate with 2 volumes of isopropanol. To ensure quantitative yields of small quantities of DNA (< 100 ng), carrier RNA (1 µg) can be added to the solution.
    5. Mix thoroughly, chill and centrifuge at 15,000 X g for 15 minutes.
    6. Remove the supernatant, wash the pellet with cold 70% isopropanol and dry the pellet at room temperature.
    7. The pellet can be resuspended in TE or any buffer necessary for subsequent manipulation.