Abstract
•ORP decreases the catalytic efficiency of BSA, however it increases for HSA.•The quenching mechanism was static for HSA and dynamic for BSA with ORP.•The binding of ORP with serum albumins (BSA/HSA) was enthalpy driven.
Herein, we have explored the comparative effect of antihistaminic drug, orphenadrine (ORP) on serum albumins - human serum albumin (HSA) and bovine serum albumin (BSA). The interaction between ORP and proteins was characterized using steady state fluorescence spectroscopy, UV-visible spectroscopy, circular dichroism (CD) and molecular docking methods. Binding constant for BSA-ORP and HSA-ORP systems were found to be 2.78 × 104 Lmol−1 and 3.09 ×104 Lmol−1, respectively. Far UV-CD results showed that the secondary structure of HSA becomes more compact in presence of ORP, however, the secondary structure of BSA decreases in presence of ORP. The functionality of both the proteins changes in presence of ORP which was confirmed by esterase like activity of BSA/HSA. Competitive binding results showed that ORP binds to Sudlow site I (subdomain II) of both BSA and HSA. The computational study was carried out to further our understanding of the experimental work.
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