Trichloroacetic acid treatment as a tricky way for rapid purification of 1N/4R tau protein

•A new efficient method for purification of 1N/4R tau isoform was developed.•We found out that 1N/4R tau isoform does not precipitate with glycerol.•We purified 1N/4R tau isoform by using TCA as a precipitation reagent.•The precipitation of tau was influenced by the presence of other cell components.•Auto-induction system was found suitable for expression of tau.

Tau protein consists of six different isoforms and each one has particular physiological roles. In order to analyze the specific function of each single isoforms, large quantity of highly purified tau isoforms is essential. Many studies have been done to purify tau isoforms by heat treatment, followed by perchloric acid and glycerol precipitation. We found out that 1N/4R tau is soluble in glycerol, that is why mentioned methods do not work for purifying this isoform. In this study, large amounts of active and highly purified (97%) 1N/4R tau protein has been prepared by utilization of trichloroacetic acid as precipitating agent.