Investigation of the Binding Profiles of AZD2184 and Thioflavin T with Amyloid-β(1-42) Fibril by Molecular Docking and Molecular Dynamics Methods.
Detecting deposits of amyloid β fibrils in the brain is of paramount importance for an early diagnosis of Alzheimer's disease. A number of PET tracers have been developed for amyloid imaging, but many suffer from poor specificity and large signal to background ratio. Design of tracers with specificity and improved binding affinity requires knowledge about various potential binding sites in the amyloid β fibril available for the tracers and the nature of the local microenvironment of these sites. In this study we investigate the local structure of fibrils using two important probes, namely, thioflavin T (a fluorescent probe) and AZD2184 (a PET tracer). The target structures for amyloid-β(1-42) fibril are based on reported NMR solution models. By explicitly considering the effect of fibril flexibility on the available binding sites for all these models, the binding affinity of these probes has been investigated. The binding profiles of AZD2184 and thioflavin T were studied by molecular docking and molecular dynamics simulation methods. The two compounds were found to bind at the same sites of the fibril: three of which are within the fibril, and one is on the two sides of the Met35 residue on the surface. The binding affinity of AZD2184 and thioflavin T is found to be higher at the core sites than on the surface due to more contact residues. The binding affinity of AZD2184 is much higher than that of thioflavin T at every site due to electrostatic interaction and spatial restriction, which is in good agreement with experimental observation. However, the structural change of thioflavin T is much more significant than that of AZD2184, which is the chemical basis for its usage as a fluorescent probe. The ramifications of these results for the design and optimization of PET radioligands and fluorescent probes are briefly discussed.
Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology , SE-10691 Stockholm, Sweden.
Guanglin
G
Kuang
Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology , SE-10691 Stockholm, Sweden.
N Arul
NA
Murugan
Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology , SE-10691 Stockholm, Sweden.
Yaoquan
Y
Tu
Karolinska Institute, Department of Neurobiology, Care Sciences and Society, Center of Alzheimer Research, Translational Alzheimer Neurobiology, Karolinska University Hospital Huddinge , S-141 86 Stockholm, Sweden.
Agneta
A
Nordberg
Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology , SE-10691 Stockholm, Sweden.
Hans
H
Ågren
D000544:Alzheimer Disease / Q000175:diagnosis / Q000000981:diagnostic imaging; D000631:Aminopyridines / Q000737:chemistry*; D016229:Amyloid beta-Peptides / Q000737:chemistry*; D052160:Benzothiazoles / Q000737:chemistry*; D015195:Drug Design; D004548:Elasticity; D005456:Fluorescent Dyes / Q000737:chemistry*; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D010446:Peptide Fragments / Q000737:chemistry*; D049268:Positron-Emission Tomography; D011485:Protein Binding; D019275:Radiopharmaceuticals / Q000737:chemistry*; D055672:Static Electricity; D013844:Thiazoles / Q000737:chemistry*
C539976:2-(6-(methylamino)pyridin-3-yl)-1,3-benzothiazol-6-ol; D000631:Aminopyridines; D016229:Amyloid beta-Peptides; D052160:Benzothiazoles; D005456:Fluorescent Dyes; D010446:Peptide Fragments; D019275:Radiopharmaceuticals; D013844:Thiazoles; C075222:amyloid beta-protein (1-42); C009462:thioflavin T