title: Aminoalcohol-Induced Activation of Organophosphorus Hydrolase (OPH) towards Diisopropylfluorophosphate (DFP).
abstract: Aminoalcohols have been addressed as activating buffers for alkaline phosphatase. However, there is no record on the buffer activation regarding organophosphorus hydrolase (OPH). Here we reported the activating effects of aminoalcohols on OPH-catalyzed hydrolysis of diisopropylfluorophosphate (DFP), an analog molecule of G-type warfare agents. The kinetic parametors kcat, Vmax and kcat/Km in the OPH reaction were remarkably increased in the buffers (pH 8.0, 25°C) containing aminoalcohols with C2 between nitrogen (N) and oxygen (O) in their structures, including triethanolamine (TEA), diethanolamine, monoethanolamine, 1-amino-2-propanol, 2-amino-2-methyl-1-propanol, and triisopropanolamine. In contrast, much lower or no rate-enhancing effects were observed in the adding of amines, alcohols, amine/alcohol mixtures, or 3-amino-1-propanol (C3 between N and O). The 300 mM TEA further increased DFP-degrading activities of OPH mutants F132Y and L140Y, the previously reported OPH mutants with desirable activities towards DFP. However, the treatment of ethylenediaminetetraacetate (EDTA) markedly abolished the TEA-induced activation of OPH. The product fluoride effectively inhibited OPH-catalyzed hydrolysis of DFP by a linear mixed inhibition (inhibition constant Ki ~ 3.21 mM), which was partially released by TEA adding at initial or later reaction stage. The obtained results indicate the activation of OPH by aminoalcohol buffers could be attributed to the reduction of fluoride inhibition, which would be beneficial to the hydrolase-based detoxification of organophosphofluoridate.
authors.affiliation: Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei, P. R. China.|Department of Biochemistry, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, Hubei, P.R. China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Li
authors.affiliation: Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei, P. R. China.
authors.forename: Yunze
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, Hubei, P. R. China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Song
authors.affiliation: Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, Hubei, P. R. China.
authors.forename: Liangqiu
authors.initials: L
authors.lastname: Lu
authors.affiliation: Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei, P. R. China.
authors.forename: Deli
authors.initials: D
authors.lastname: Liu
authors.affiliation: Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei, P. R. China.
authors.forename: Yongze
authors.initials: Y
authors.lastname: Yuan
mesh_terms: D000605:Amino Alcohols / Q000494:pharmacology*; D043303:Aryldialkylphosphatase / Q000378:metabolism*; D004789:Enzyme Activation; D006868:Hydrolysis; D007531:Isoflurophate / Q000378:metabolism*; D007700:Kinetics; D045249:Sphingobacterium / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D000605:Amino Alcohols; D007531:Isoflurophate; D043303:Aryldialkylphosphatase