Chromatrap, a business unit of Porvair Sciences, has published a new technical article that discusses and describes methodologies to increase Chromatin Immunoprecipitation (ChIP) efficiency by making sure chromatin in your samples is sheared to the correct size range.

The authors describe how for every chromatin preparation it is essential to check the chromatin is sheared to fragments between 100-500 bp. They emphasise using a microfluidics platform is the most accurate measure of quantifying DNA.

Problems associated with over or under sheared Chromatin fragments are discussed and a protocol for optimised enzymatic shearing described. As some cells are resistant to lysis the authors also describe an optimised sonication methodology to ensure a successful ChIP result.

Launched worldwide in 2012 - Chromatrap® solid-state ChIP technology has been shown by a growing number of research groups worldwide to be more efficient than conventional bead-based methods. This is because the solid phase porous polymer, functionalized with either protein A or G, provides a greater surface area for chromatin antibody binding with very low non-specific binding. In addition, it uses a spin column approach, offering significant speed, process and carry-over advantages over sepharose or magnetic beads. DNA pull down with Chromatrap® is up to 25 times more than conventional methods, whilst the signal to noise ratio for DNA enrichment is 2 to 3 times better, even with low chromatin samples between 50ng to 3000ng per immunoprecipitation.

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