Capillary Electrophoresis-Frontal Analysis (CE-FA) and Molecular Docking Studies on the Albumin-Binding Properties of Dopamine and Serotonin

Dopamine and serotonin are neurotransmitters that are crucial for numerous physiological processes, including mood regulation, reward, and motor function. Dysregulation of these neurotransmitters is associated with various neuropsychiatric disorders. Albumin in plasma modulates the bioavailability of drugs and free concentrations of bioactive constituents. This study aimed to characterize the interactions of dopamine and serotonin with bovine serum albumin. Capillary electrophoresis in the frontal analysis mode was utilized as an effective method to assess dopamine–bovine serum albumin and serotonin–bovine serum albumin affinity. The free neurotransmitter plateaus were distinctly separated from the bovine serum albumin–neurotransmitter complex plateaus. Free dopamine and serotonin concentrations were determined by monitoring the heights of their respective plateaus. In contrast, the bound concentrations were calculated from the difference between the total and free plateau heights. Dopamine and serotonin were found to bind to bovine serum albumin at independent sites with binding constant values of 1.90 × 10³ and 2.90 × 10³ L/mol, respectively. Additionally, an in silico molecular docking approach revealed the binding sites for dopamine and serotonin near the glutamic acid-291 and serine-428 residues of bovine serum albumin, respectively.