title: The effect of trifluoroethanol on tyrosinase activity and conformation: inhibition kinetics and computational simulations.
abstract: We studied the inhibitory effects of trifluoroethanol (TFE) on the activity and conformation of tyrosinase. TFE increased the degree of secondary structure of tyrosinase, which directly resulted in enzyme inactivation. A reciprocal study showed that TFE inhibited tyrosinase in a slope-parabolic mixed-type inhibition manner (K (I) = 0.5 +/- 0.096 M). Time-interval kinetic studies showed that the inhibition was best described as first order with biphasic processes. Intrinsic and 1-anilinonaphthalene-8-sulfonate-binding fluorescences were also measured to gain more insight into the supposed structural changes; these showed that TFE induced a conspicuous tertiary structural change in tyrosinase by exposing hydrophobic surfaces. We also predicted the tertiary structure of tyrosinase and simulated its docking with TFE. The docking simulation was successful with significant scores (binding energy for Autodock4 = -4.75 kcal/mol; for Dock6 = -23.07 kcal/mol) and suggested that the TRP173 residue was mainly responsible for the interaction with TFE. Our results provide insight into the structure of tyrosinase and allow us to describe a new inhibition strategy that works by inducing conformational changes rather than targeting the active site of the protein.
authors.affiliation: Department of Environmental Health, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou 510515, People's Republic of China.
authors.forename: Zhi-Rong
authors.initials: ZR
authors.lastname: Lü
authors.forename: Long
authors.initials: L
authors.lastname: Shi
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Daeui
authors.initials: D
authors.lastname: Park
authors.forename: Jong
authors.initials: J
authors.lastname: Bhak
authors.forename: Jun-Mo
authors.initials: JM
authors.lastname: Yang
authors.forename: Yong-Doo
authors.initials: YD
authors.lastname: Park
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Zhou
authors.forename: Fei
authors.initials: F
authors.lastname: Zou
mesh_terms: D003198:Computer Simulation; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation / Q000187:drug effects; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship; D013499:Surface Properties; D013997:Time Factors; D014270:Trifluoroethanol / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D014270:Trifluoroethanol; D014442:Monophenol Monooxygenase