Decoding the interaction of an imidazo-pyrimidine derivative with serum proteins: Spectroscopic, computational and structure-activity relationship analysis

In the present article, we have tried to theoretically analyze the structure-function relationship of a novel imidazo pyrimidine derivative, IPD, and decipher its interactions with two serum proteins, BSA and HSA, spectroscopically. IPD is almost non-fluorescent in a polar environment, but its fluorescence enhancement is significant in non-polar mediums like proteins. Steady-state fluorometric investigations indicate a strong binding interaction between the probe, IPD, and serum proteins, with HSA being more strongly bound to IPD. This stronger binding affinity of the IPD-HSA complex than compared to the IPD-BSA complex was corroborated through denaturation and quenching studies, too. In silico molecular docking interactions also reveal a similar stronger binding affinity in HSA than BSA. This is attributed to the probe residing in a more hydrophobic region in HSA; thus, the pi and alkyl interactions are stronger in HSA than in BSA.