Topoisomerase II Beta (TOP2b) is a nuclear enzyme critical for resolving DNA topological constraints during transcription, replication, and chromatin remodeling. It catalyzes DNA double-strand breakage and religation, regulating genomic stability and gene expression. Expressed ubiquitously, TOP2b is essential for embryonic development and neuronal differentiation, with dysregulation linked to cancer and neurodegenerative diseases. Emerging evidence highlights its role in mediating DNA damage responses and maintaining epigenetic integrity. TOP2b interacts with androgen receptor (AR) to modulate AR-targeted gene transcription in hormone-responsive tissues, facilitating transcriptional activation.To detect the activity of recombinant TOP2b, a functional ELISA assay was performed to evaluate the interaction between recombinant human TOP2b and recombinant human AR.Briefly, biotin-linked TOP2b were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100µl were then transferred to AR-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST 3 times and incubation with Streptavidin-HRP for 30min, then wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50µl stop solution to the wells and read at 450nm immediately. The binding activity of TOP2b and AR was shown in Figure 1, the EC50 for this effect is 0.0269µg/mL.