Biliverdin Reductase A (BLVRA) is a crucial cytoplasmic enzyme involved in the heme catabolism pathway. It specifically catalyzes the reduction of biliverdin (a green tetrapyrrole pigment) to bilirubin (a yellow antioxidant) using NADPH as a cofactor. Beyond this primary metabolic role, BLVRA exhibits potent antioxidant and anti-inflammatory properties by scavenging reactive oxygen species (ROS) and modulating key signaling pathways like NF-κB. It plays protective roles in oxidative stress-related conditions, including cardiovascular diseases, neurodegenerative disorders, and diabetes. BLVRA's pleiotropic functions make it a significant player in cellular defense mechanisms against oxidative damage.Besides,Biliverdin Reductase B (BLVRB) has been identified as an interactor of BLVRA, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant mouse BLVRA and recombinant human BLVRB. Briefly, BLVRA was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to BLVRB-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-BLVRA pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 μL stop solution to the wells and read at 450/630nm immediately. The binding activity of recombinant mouse BLVRA and recombinant human BLVRB was shown in Figure 1, the EC50?for this effect is 0.121μg/mL.