Chromatin immunoprecipitation (ChIP) is an important technique for the analysis of chromatin-associated proteins in their native chromatin context. Existing ChIP methods utilize agarose beads to capture the antibody/chromatin complexes, but spin-washing of agarose beads is tedious and slow. In addition, DNA isolated through these methods must be further purified (by laborious phenol/chloroform extraction and precipitation or using expensive spin columns) prior to PCR analysis. We have developed a greatly simplified ChIP protocol that utilizes magnetic protein G–coated beads for antibody capture. This dramatically reduces washing time and enables the use of multichannel pipetting, so that many samples can be assayed simultaneously (Figure 1).

Chromatin immunoprecipitation (ChIP) is an important technique for the analysis of chromatin-associated proteins in their native chromatin context. Existing ChIP methods utilize agarose beads to capture the antibody/chromatin complexes, but spin-washing of agarose beads is tedious and slow. In addition, DNA isolated through these methods must be further purified (by laborious phenol/chloroform extraction and precipitation or using expensive spin columns) prior to PCR analysis. We have developed a greatly simplified ChIP protocol that utilizes magnetic protein G–coated beads for antibody capture. This dramatically reduces washing time and enables the use of multichannel pipetting, so that many samples can be assayed simultaneously (Figure 1).

The ChIP-IT™ Express method improves on traditional ChIP by reducing or eliminating several time-consuming steps. The magnetic beads have much lower background than traditional agarose beads, so pre-clearing and blocking of the chromatin are no longer necessary. Wash steps are faster and fewer because centrifugation is replaced by magnetic pull-down, significantly reducing the amount of hands-on time. In addition, improvement of the chromatin elution and proteinase K treatment steps has completely eliminated the need for a separate DNA purification step after ChIP is complete (Figure 2). This not only saves time, it also minimizes manipulations and eliminates DNA loss that occurs during purification, both of which help ensure sample-to-sample consistency and the reproducibility of your experiments.

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ChIP-IT Express Kits transform ChIP from a labor-intensive protocol that is appropriate for only a small number of samples into a rapid method that is suitable for experiments requiring multiple samples (e.g., studies of pathway induction, time-course experiments, etc.). This novel magnetic bead–based protocol is the basis for a family of groundbreaking kits that dramatically improve your ability to ask important questions about chromatin protein localization, transcription factor function, and the role of histone modifications in the regulation of genome function.

We have recently introduced two innovative new kits that enable you to ask questions that were previously difficult to address due to the technically challenging nature of the experiments. ChIP-IT Express HT allows you to rapidly and efficiently process a large number of ChIP reactions in a fast, reproducible high-throughput format. It combines the efficiency of the ground-breaking magnetic bead–based ChIP-IT Express Kit with a 96-well plate format. The new Re-ChIP-IT Kit enables sequential chromatin immunoprecipitations to be performed using two different antibodies, so you can assay for the simultaneous presence of two proteins or distinct histone modifications at the same genomic region of interest. These new kits are part of Active Motif's continuing commitment to develop cutting edge kits to perform your important experiments. For details on chromatin IP kits from Active Motif, visit www.activemotif.com/chipit.

Address correspondence to Active Motif, Inc., 1914 Palomar Oaks Way, Suite 150, Carlsbad, CA 92008, USA; Tel.: (877) 222-9543; [email protected], www.activemotif.com.