Immobilization of the enzyme GpdQ on magnetite nanoparticles for organophosphate pesticide bioremediation.
Annually thousands of people die or suffer from organophosphate (pesticide) poisoning. In order to remove these toxic compounds from the environment, the use of enzymes as bioremediators has been proposed. We report here a Ser127Ala mutant based on the enzyme glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes. The mutant, with improved metal binding abilities, has been immobilized using glutaraldehyde on PAMAM dendrimer-modified magnetite nanoparticles. The immobilized system was characterized using elemental analysis as well as infrared, transmission electron and X-ray photoelectron spectroscopies. The amount of GpdQ that was immobilized with the optimized procedure was 1.488 nmol per g MNP. A kinetic assay has been designed to evaluate the activity of the system towards organophosphoester substrates. The specific activity towards BPNPP directly after immobilization was 3.55 μmol mg(-1)min(-1), after one week 3.39 μmol mg(-1)min(-1) and after 120 days 3.36 μmol mg(-1)min(-1), demonstrating that the immobilized enzyme was active for multiple cycles and could be stored on the nanoparticles for a prolonged period.
School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane QLD 4072, Australia.
Lena J
LJ
Daumann
Department of Chemistry and Biochemistry, Middlebury College, Middlebury VT 05753, USA.
James A
JA
Larrabee
Research School of Chemistry, Australian National University, Canberra 0200, Australia.
David
D
Ollis
School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane QLD 4072, Australia.
Gerhard
G
Schenk
School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane QLD 4072, Australia. Electronic address: gahan@uq.edu.au.
Lawrence R
LR
Gahan
D001673:Biodegradation, Environmental; D050091:Dendrimers; D021902:Enterobacter aerogenes / Q000201:enzymology; D004800:Enzymes, Immobilized / Q000737:chemistry*; D005976:Glutaral / Q000737:chemistry; D007700:Kinetics; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D009154:Mutation; D009596:Nitrophenols / Q000378:metabolism; D010755:Organophosphates / Q000737:chemistry / Q000378:metabolism*; D010575:Pesticides / Q000737:chemistry / Q000378:metabolism*; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D056951:Photoelectron Spectroscopy; D012694:Serine / Q000235:genetics; D018508:Water Purification / Q000379:methods
D050091:Dendrimers; D004800:Enzymes, Immobilized; D058185:Magnetite Nanoparticles; D009596:Nitrophenols; D010755:Organophosphates; C104700:PAMAM Starburst; D010575:Pesticides; D012694:Serine; C002887:bis(4-nitrophenyl)phosphate; D010727:Phosphoric Diester Hydrolases; C038133:glycerophosphodiester phosphodiesterase; D005976:Glutaral
Bioremediation; Magnetite nanoparticles; Metalloenzyme; Organophosphate pesticide