Glycation reduces the binding dynamics of aflatoxin B1 to human serum albumin: a comprehensive spectroscopic and computational investigation

Aflatoxin B1 (AFB1), a potent mutagen, is synthesized by Aspergillus parasiticus and Aspergillus flavus. Human serum albumin (HSA) is a globular protein with diverse roles. As AFB1 is ingested with food and is transported in the body via blood, it becomes pertinent to comprehend the effect of the binding of this toxin on the structure and conformation of HSA, which may help to get insight into the toxic effect of the exposure of the mycotoxin. In this study, multi-spectroscopic approaches have been used to evaluate the binding efficiency of AFB1 with both the native HSA (nHSA) and the glycated HSA (gHSA). Steady-state fluorescence spectroscopy reveals the static type of fluorescence quenching in the fluorescence emission spectra of nHSA and gHSA in the presence of AFB1. The binding constant (Kb) is calculated to be 6.88 × 104 M-1 for nHSA, while a reduced Kb value of 2.95 × 104 M-1 has been obtained for gHSA. The circular dichroism study confirms the change in the secondary structure of nHSA and gHSA in the presence of AFB1, followed by alterations in the melting temperature (Tm) of nHSA and gHSA. In silico computational findings envisaged the amino acid residues and bonds involved in the binding of nHSA and gHSA with AFB1. The comprehensive study analyzes the binding effectiveness of AFB1 with nHSA and gHSA and shows reduced binding of AFB1 to gHSA.Communicated by Ramaswamy H. Sarma.