In an MST assay, Bractoppin demonstrates nanomolar potency in displacing the cognate BACH1 phosphopeptide substrate from the BRCA1 tBRCT, with a binding IC50 value of 74 nM^[1].

In a selectivity profile assessed through competitive MST assay, Bractoppin (0-100 μM) shows no observable binding to fluorescently labeled tBRCT domains from MCPH1, TOPBP1 7/8, ECT2, or TOPBP1 1/2^[1].

Bractoppin (100μM) selectively suppresses damage-induced BRCA1 foci formation, while it has minimal impact on the radiation-induced accumulation of MDC1 at DNA damage sites. Similarly, Bractoppin shows negligible influence on the radiation-induced recruitment of TOPBP1 (a protein containing multiple, structurally related tBRCT domains)^[1].

Bractoppin (10-100 μM; 0.5 hr before radiation (32 hours)) dose-dependently suppresses 4Gy radiation-induced G2 arrest. The percentage of G2-arrested cells decreases to 64%, 42%, and 25% for 10 μM, 30 μM, and 100 μM, respectively^[1].