Abstract: The present invention provides a method for enrichment and isolation of endogenous transcription factors and their complexes. Also, this invention provides corresponding tandem arrays of concatenated transcription factor response elements (catTFRE). The method employs the property of transcription factors binding to sequence-specific DNA elements during regulation of gene expression. The catTFREs are designed and synthesized as concatenate dual copies of DNA response elements for various transcription factors. The DNA sequence of synthesized catTFRE is cloned to a target vector. Biotinylated catTFRE with 200 bp arms is prepared by PCR strategy. For enrichment and isolation of endogenous transcription factors and their complexes, the biotinylated catTFRE is immobilized to streptavidin-coated magnetic beads and then incubated with nuclear extract. Thereby endogenous transcription factors and their complexes are isolated from nuclear extract.