Acetylcholinesterase from Curimatã Fish Brain (Prochilodus Brevis) as Potential Biocatalyst for Voltammetric Biosensor Construction
Journal Title: Biomedical Journal of Scientific & Technical Research (BJSTR) - Year 2018, Vol 8, Issue 3
Abstract
Background: The AChE (acetylcholinesterase) is a serine hydrolase responsible for terminating neurotransmission by hydrolyzing the acetylcholine released on synaptic cleft. Studies of AChE as a target of pesticide toxicity have yielded several practical outcomes and are the basis for constructing biosensors. These devices are primarily designed to determine and quantify the inhibition of AChE by toxic chemicals. Objective: to construct a biosensor based on acetylcholinesterase from the brain of the Prochilodus brevis fish, and to use the same as biomarker of agrochemicals that inhibit the enzyme. Methods: Acetylcholinesterase was isolated from curimata fish brain (prochilodus brevis) and partially purified using amonium sulfate precipitation followed by size-exclusion chromatography (ChE1). AChE from curimata fish brain was directly immobilizes on the surface of glassy carbon electrode modified with multi-walled carbon nanotubes. Results: Acetylcholinesterase was characterized as having a specific activity of 0.194U/mg. The optimum activity was found at pH 8.5, phosphate buffer 0.7^M, 28°C and exhibited a thermostability at 37°C. The glassy carbon modified electrode exhibits excellent electrocatalytic activity to the increase of thiocholine, with a linear response in the 0.05 mM to 0.85 mM concentration range, with a 73^M limit of detection and with a 240^M limit of quantification. Acetylcholinesterase (AChE) is present in all vertebrates, particularly in the muscles and nervous tissues [1]. AChE is a serine hydrolase (EC. 3.1.1.7) localized between the nerve terminal and post-synaptic membrane responsible for terminating neurotransmission by hydrolyzing the acetylcholine released on synaptic cleft, is being one of the most efficient enzyme reactions [1,2]. Studies of AChE as a target of pesticide toxicity have yielded several practical outcomes and are the basis for constructing biosensors. These devices are primarily designed to determine and quantify the inhibition of AChE by toxic chemicals. Depending on the extraction source, these enzymes can have different substrate specificity and susceptibility to inhibitors [3]. The several different molecular forms which are dependent of enzyme gene shown variable catalytic properties of AChE [4,5]. Apart these, the physiological meaning of different forms and molecular interactions allow various types of AChE in different tissues and physiological conditions [4]. These various AChE forms have been a motivation for build a voltammetry biosensor applied for a specific ecosystem. Fish are a group of great importance in environmental toxicity evaluations, as well as being present in various environments and present wide geographical distribution, still participate in different trophic levels ofthe food chain, being regarded as excellent biological models to study. Prochilodus brevis is a native fish of the San Francisco river, one of the largest watercourses of Brazil, has a huge regional importance of viewpoints ecological, economic and social. Besides, the effluents generated by the disorderly occupation are contamination promoted using agrochemicals of the agricultural activity in the surroundings of the river, which generates a concern about the contamination of the aquatic systems. The present work proposes to construct a biosensor based on acetylcholinesterase from the brain of the Prochilodus Brevis fish, native to the region, and to use the same as biomarker of agrochemicals that inhibit the enzyme, providing greater specificity. The electrochemical system builded will provide a biosensor for sensing thiocholine from AChE isolated of a real biological model.
Authors and Affiliations
Giovanni Ortiz Leoncini, Emanuella Gomes da Silva, Sonia Salgueiro Machado, Fabiane Caxico de Abreu
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