New England Biolabs offers several products for detection of RNA.
The p19 miRNA Detection Kit (NEB #E3312) uses the high affinity binding properties of the p19 protein to detect miRNAs that form hybrids with a specific probe. The p19 is expressed as an amino terminal fusion of the maltose binding protein (MBP) and a carboxy terminal fusion of the chitin binding domain (CBD). The MBP aids in p19 purification and the CBD allows p19 to bind very tightly to Chitin Magnetic Beads (NEB #E8036). The p19 fusion protein bound to chitin magnetic beads (p19 beads) has the same binding properties as the native p19; it selectively binds siRNAs that are 21–23 bases long but does not bind ssRNA or dsDNA of the same length (2,3). After siRNA or hybrids of miRNA:RNA-probe are bound to the p19 beads, they can easily be isolated in a small volume using a Magnetic Separation Rack (NEB #S1506) or (NEB #S1509) and eluted with SDS. The p19 beads can also enrich siRNAs greater than 3,000 fold from a mixture of total cytoplasmic RNA.
NEB’s Streptavidin Magnetic Beads (NEB #S1420) are 1 µm superparamagnetic particles covalently coupled to a highly pure form of streptavidin. Captured substrates can be useful as ligands in subsequent experiments, including mRNA isolation and the capture of primary or secondary antibodies.
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