Anticancer altretamine recognition by bovine serum albumin and its role as inhibitor of fibril formation: Biophysical insights

Abstract Binding of anticancer drug altretamine with bovine serum albumin (BSA) and its inhibitory effect on fibrillation of the protein has been studied by using a combination of spectroscopic and calorimetric methods. Altretamine is observed to bind with BSA with a moderate binding affinity of the order of 10 5 , which is weakly temperature dependent. Circular dichroism, fluorescence spectroscopic and dynamic light scattering methods have been employed to monitor the conformational change in the protein. Time correlated single photon counting measurements have confirmed ground state complexation of the drug with the protein. Docking studies have led to identification of binding sites on BSA at site III in domain IB. Thioflavin T (ThT) fluorescence emission has been used as a tool to monitor the formation of fibrils/aggregates in BSA. It is observed that anticancer drug altretamine can also act as an inhibitor of fibrillation in BSA and hence can be useful in the treatment of neuro-degenerative diseases. Differential scanning calorimetry has been employed to study the thermal transitions of BSA at different stages of the fibrillation process with and without altretamine to obtain insights into the extent of stabilisation provided by the drug to the protein in native, nucleation/elongation and matured state in the fibrillation process.