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Services – ProNex Magnetic Beads


• ProNex Size-Selective Purification System

• RNA & ssDNA purification by ProNex Beads

• Online Submission Request

• Physical Submission of Samples


ProNex Size-Selective Purification System

The ProNextm Size-Selective Purification System enables rapid and efficient magnetic resin-based purification of dsDNA for NGS, PCR and general molecular biology applications. Based on Promega's comparison data to AMPuretm XP beads, the novel reagent formulation of ProNex beads provides significantly improved selectivity, reproducibility and yield.

ProNex beads were developed to remove gDNA from "short-read" NGS libraries, and technical support states that the product removes >99% of intact genomic DNA at initial levels up to 200 ng/µl. By varying the volume ratio of "ProNex::Sample", users can control what size DNA is retained or eliminated (from 100bp to 750bp). This enables NGS library and PCR fragment cleanup, as well as dual size-selection of libraries.

Genomic DNA: ProNex beads can also be used to purify genomic DNA. For instance, Promega's Oxford Nanopore Sequencing application note (vendor pdf) outlines the procedure in which the goal was the retention of high-quality intact genomic DNA. Essentially, one follows the basic "single-selection" protocol, using whatever ratio will retain the smallest desired fragments from the genomic DNA.

When testing ProNex, the Genomics Core found that certain protocol modifications or clarifications improved results (LSU_ProNex_Dual-Size-Select_100-700bp.docx). In particular, the standard protocol left enough surface tension in the sample to cause tiny amounts of the magnetic beads to detach from the main bead mass on the magnet, resulting in residual beads in the cleaned samples. This problem was eliminated by first bringing samples to a final concentration of ~0.005% Tween-20, which broke the surface tension of the sample.

RNA & ssDNA Purification by ProNex Beads

ProNex beads can be used to purify RNA and ssDNA from various contaminates (e.g., buffers, proteins, salts) and low-molecular-weight nucleic acid fragments (e.g., adapters, oligonucleotides, nucleotides). Fragments smaller than ~100-nt will be lost; thus, microRNAs and the lower-fraction of the small RNAs will be eliminated with this protocol.

RNA samples will be eluted in The RNA Storage Solution (ThermoFisher, AM7000 – 1 mM sodium citrate, pH 6.4) for improved stability. DNA samples will be eluted in nuclease-free TVLE (10 mM Tris, 0.005 mM EDTA, pH 8). Both buffers will also contain Tween-20 at 0.005 percent.

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Online Submission Request

  • Log In to the website, and click on "Services Page":
    • Make the necessary 'selections'.
    • For dsDNA samples, specify your size-selection parameters in the "Client Memo" field.
    • Specify whether samples should be stored post-processing at 4oC or at -20oC.
    • Click the 'check box', and submit your request.
  • If you make an error in your request, you may revise that request if you do so before we begin processing it.
  • You will receive an automated email when your samples are processed and ready for pick-up.

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    Physical Submission of Samples

  • Tubes:  Best practice is to store samples Eppendorf LoBind tubes (or equivalent) to minimize adsorption of nucleic acids onto the tube walls. For submission to the Core, samples may be submitted in 0.2-ml, 0.5-ml, or 1.5-ml tubes.
  • Label Submission:  Upon successful submission of your online request, the "Submission #" will appear in your 'Submission History'. Then, label the tube rack itself with:
    • Submission #;
    • Date;
    • PI's Last Name; and,
    • Submitter name or initials.
  • Delivery site:  Transfer tubes to a Genomics Core rack (taking your own rack back to your lab), and put samples in the Mini-fridge (by sink) in the Genomics Core (A628 Life Science Annex).

    [Note: If the Core is locked, put your samples in the plastic "After-Hours" GC drop-box located in the adjacent Cold Room (beside sink, Rm. A650).]

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