title: Discovery of Small Molecules for Fluorescent Detection of Complement Activation Product C3d.
abstract: Complement activation plays a major role in many acute and chronic inflammatory conditions. C3d, a terminal product of complement activation, remains covalently attached to cells and is an excellent biomarker of complement-mediated inflammation. We employed a virtual high-throughput screening protocol to identify molecules with predicted binding to complement C3d and with intrinsic fluorescence properties to enable detection. Pharmacophore models were developed based on known C3d-ligand interactions and information from computational analysis of structural and molecular dynamics data. Iterative pharmacophore-based virtual screening was performed to identify druglike molecules with physicochemical similarity to the natural C3d ligand CR2. Hits from the pharmacophore screens were docked to C3d and ranked based on predicted binding free energies. Top-ranked molecules were selected for experimental validation of binding affinity to C3d, using microscale thermophoresis, and for their suitability to become molecular imaging agents, using fluorescence spectroscopy. This work serves as a foundation for identifying additional fluorescent molecules with high-affinity for C3d that will subsequently be explored as noninvasive in vivo diagnostics of complement-mediated inflammation, for spatiotemporal monitoring of disease progression, and for targeting therapeutics to sites of inflammation.
authors.affiliation: Department of Bioengineering, University of California , Riverside, California 92521, United States.|Department of Medical Microbiology, University Medical Center, Utrecht , 3584 CX Utrecht, The Netherlands.
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Gorham
authors.affiliation: Department of Bioengineering, University of California , Riverside, California 92521, United States.
authors.forename: Vicente
authors.initials: V
authors.lastname: Nuñez
authors.affiliation: Division of Mechanics, Research Center for Applied Sciences and Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan.|School of Pharmacy, National Taiwan University , Taipei 100, Taiwan.
authors.forename: Jung-Hsin
authors.initials: JH
authors.lastname: Lin
authors.affiliation: Department of Medical Microbiology, University Medical Center, Utrecht , 3584 CX Utrecht, The Netherlands.
authors.forename: Suzan H M
authors.initials: SH
authors.lastname: Rooijakkers
authors.affiliation: Department of Bioengineering, University of California , Riverside, California 92521, United States.
authors.forename: Valentine I
authors.initials: VI
authors.lastname: Vullev
authors.affiliation: Department of Bioengineering, University of California , Riverside, California 92521, United States.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Morikis
mesh_terms: D003167:Complement Activation; D015933:Complement C3d / Q000032:analysis*; D005456:Fluorescent Dyes / Q000737:chemistry*; D008024:Ligands; D062105:Molecular Docking Simulation; D011487:Protein Conformation; D054852:Small Molecule Libraries / Q000737:chemistry*; D013329:Structure-Activity Relationship
chemical_list: D005456:Fluorescent Dyes; D008024:Ligands; D054852:Small Molecule Libraries; D015933:Complement C3d