Interaction of a tyrosine kinase inhibitor, vandetanib with human serum albumin as studied by fluorescence quenching and molecular docking.
Interaction of a tyrosine kinase inhibitor, vandetanib (VDB), with the major transport protein in the human blood circulation, human serum albumin (HSA), was investigated using fluorescence spectroscopy, circular dichroism (CD) spectroscopy, and molecular docking analysis. The binding constant of the VDB-HSA system, as determined by fluorescence quenching titration method was found in the range, 8.92-6.89 × 10(3 )M(-1) at three different temperatures, suggesting moderate binding affinity. Furthermore, decrease in the binding constant with increasing temperature revealed involvement of static quenching mechanism, thus affirming the formation of the VDB-HSA complex. Thermodynamic analysis of the binding reaction between VDB and HSA yielded positive ΔS (52.76 J mol(-1) K(-1)) and negative ΔH (-6.57 kJ mol(-1)) values, which suggested involvement of hydrophobic interactions and hydrogen bonding in stabilizing the VDB-HSA complex. Far-UV and near-UV CD spectral results suggested alterations in both secondary and tertiary structures of HSA upon VDB-binding. Three-dimensional fluorescence spectral results also showed significant microenvironmental changes around the Trp residue of HSA consequent to the complex formation. Use of site-specific marker ligands, such as phenylbutazone (site I marker) and diazepam (site II marker) in competitive ligand displacement experiments indicated location of the VDB binding site on HSA as Sudlow's site I (subdomain IIA), which was further established by molecular docking results. Presence of some common metal ions, such as Ca(2+), Zn(2+), Cu(2+), Ba(2+), Mg(2+), and Mn(2+) in the reaction mixture produced smaller but significant alterations in the binding affinity of VDB to HSA.
a Faculty of Science, Biomolecular Research Group, Biochemistry Programme, Institute of Biological Sciences , University of Malaya , Kuala Lumpur , Malaysia.
Md Zahirul
MZ
Kabir
a Faculty of Science, Biomolecular Research Group, Biochemistry Programme, Institute of Biological Sciences , University of Malaya , Kuala Lumpur , Malaysia.
Shevin R
SR
Feroz
b Faculty of Science, Bioinformatics Programme, Institute of Biological Sciences , University of Malaya , Kuala Lumpur , Malaysia.
Abdul Kadir
AK
Mukarram
a Faculty of Science, Biomolecular Research Group, Biochemistry Programme, Institute of Biological Sciences , University of Malaya , Kuala Lumpur , Malaysia.
Zazali
Z
Alias
b Faculty of Science, Bioinformatics Programme, Institute of Biological Sciences , University of Malaya , Kuala Lumpur , Malaysia.|c Faculty of Science, Centre of Research for Computational Sciences and Informatics for Biology, Bioindustry, Environment, Agriculture and Healthcare, Institute of Biological Sciences , University of Malaya , Kuala Lumpur , Malaysia.
Saharuddin B
SB
Mohamad
a Faculty of Science, Biomolecular Research Group, Biochemistry Programme, Institute of Biological Sciences , University of Malaya , Kuala Lumpur , Malaysia.|c Faculty of Science, Centre of Research for Computational Sciences and Informatics for Biology, Bioindustry, Environment, Agriculture and Healthcare, Institute of Biological Sciences , University of Malaya , Kuala Lumpur , Malaysia.
Saad
S
Tayyab
D001665:Binding Sites; D002942:Circular Dichroism; D006801:Humans; D008024:Ligands; D008670:Metals / Q000737:chemistry; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D010880:Piperidines / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation; D047428:Protein Kinase Inhibitors / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011799:Quinazolines / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D012709:Serum Albumin / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
D008024:Ligands; D008670:Metals; D010880:Piperidines; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D012709:Serum Albumin; D011505:Protein-Tyrosine Kinases; C452423:vandetanib
fluorescence quenching; fluorescence spectroscopy; human serum albumin; ligand–protein interaction; molecular docking; vandetanib