title: Interaction of firefly luciferase and silver nanoparticles and its impact on enzyme activity.
abstract: We report on the dose-dependent inhibition of firefly luciferase activity induced by exposure of the enzyme to 20 nm citrate-coated silver nanoparticles (AgNPs). The inhibition mechanism was examined by characterizing the physicochemical properties and biophysical interactions of the enzyme and the AgNPs. Consistently, binding of the enzyme induced an increase in zeta potential from -22 to 6 mV for the AgNPs, triggered a red-shift of 44 nm in the absorbance peak of the AgNPs, and rendered a 'protein corona' of 20 nm in thickness on the nanoparticle surfaces. However, the secondary structures of the enzyme were only marginally affected upon formation of the protein corona, as verified by circular dichroism spectroscopy measurement and multiscale discrete molecular dynamics simulations. Rather, inductively coupled plasma mass spectrometry measurement revealed a significant ion release from the AgNPs. The released silver ions could readily react with the cysteine residues and N-groups of the enzyme to alter the physicochemical environment of their neighboring catalytic site and subsequently impair the enzymatic activity.
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia.
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Käkinen
authors.forename: Feng
authors.initials: F
authors.lastname: Ding
authors.forename: Pengyu
authors.initials: P
authors.lastname: Chen
authors.forename: Monika
authors.initials: M
authors.lastname: Mortimer
authors.forename: Anne
authors.initials: A
authors.lastname: Kahru
authors.forename: Pu Chun
authors.initials: PC
authors.lastname: Ke
mesh_terms: D006046:Gold / Q000032:analysis; D007477:Ions; D049409:Luciferases, Firefly / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D056004:Molecular Dynamics Simulation; D017433:Protein Structure, Secondary; D012834:Silver / Q000032:analysis / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D055672:Static Electricity
chemical_list: D007477:Ions; D012834:Silver; D006046:Gold; D049409:Luciferases, Firefly