Binding site identification of metformin to human serum albumin and glycated human serum albumin by spectroscopic and molecular modeling techniques: a comparison study.
The interaction between metformin and human serum albumin (HSA), as well as its glycated form (gHSA) was investigated by multiple spectroscopic techniques, zeta potential, and molecular modeling under physiological conditions. The steady state and time-resolved fluorescence data displayed the quenching mechanism of HSA-metformin and gHSA-metformin was static. The binding information, including the binding constants, number of binding sites, effective quenching constant showed that the binding affinity of metformin to HSA was greater than to gHSA which also confirmed by anisotropy measurements. It was determined that metformin had two and one set of binding sites on HSA and gHSA, respectively. Far-UV CD spectra of proteins demonstrated that the α-helical content decreased with increasing metformin concentration. The zeta potential and resonance light scattering (RLS) diagrams provided that lower drug concentration induced metformin aggregation on gHSA surface as compare to HSA. The increase in polarizability was one of the important factors for the enhancement of RLS and the formation of drug/protein complexes. The zeta potential results suggested that both hydrophobic and electrostatic interactions played important roles in the protein-metformin complex formation. Site marker experiments and molecular modeling showed that the metformin bound to subdomain IIIA (Sudlow's site II) on HSA and gHSA.
a Faculty of Sciences, Department of Biochemistry and Biophysics , Islamic Azad University , Mashhad Branch, Mashhad , Iran.
Elaheh
E
Rahnama
Maryam
M
Mahmoodian-Moghaddam
Sabra
S
Khorsand-Ahmadi
Mohammad Reza
MR
Saberi
Jamshidkhan
J
Chamani
D001665:Binding Sites; D002942:Circular Dichroism; D004735:Energy Transfer; D005454:Fluorescence Polarization; D017127:Glycation End Products, Advanced; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007004:Hypoglycemic Agents / Q000737:chemistry*; D008687:Metformin / Q000737:chemistry*; D062105:Molecular Docking Simulation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012709:Serum Albumin / Q000737:chemistry*; D013816:Thermodynamics; D000093423:Glycated Serum Albumin
D017127:Glycation End Products, Advanced; D007004:Hypoglycemic Agents; D012709:Serum Albumin; D008687:Metformin; D000093423:Glycated Serum Albumin
HSA; gHSA; metformin; molecular modeling; spectroscopy; zeta potential