Use of substitute Nonidet P-40 nonionic detergents in intracellular tubulin polymerization assays for screening of microtubule targeting agents.

Shell Chemical Company Nonidet P-40 has been used for decades in many biochemical assays as a nonionic, nondenaturing detergent; however, Shell no longer manufactures this product. Four commercially available substitutes were investigated and their activities titrated in an intracellular tubulin polymerization assay. Although claimed by the supply companies to be identical to the Shell Nonidet P-40, all four substitutes were about 10-fold more potent and needed to be diluted accordingly. As microtubule targeting drugs are a major class of anticancer agent, and many researchers use the intracellular tubulin polymerization assay, this information is important to help troubleshoot assay development with the new substitutes. As the Shell Nonidet P-40 has been used in many biochemical buffers, these results will be of general interest to the biochemical, cell, and molecular research community.