Acetylcholinesterase (AChE; EC 3.1.1.7) is a serine hydrolase, whose main function is to modulate neurotransmission at cholinergic synapses. It is, therefore, the primary target of some pesticides and heavy metals. Its inhibition in aquatic organisms has been used as an indicator of the presence of these pollutants in water bodies. The present study aimed to characterize physicochemical and kinetic parameters of brain AChE in the benthic fish Hoplosternum littorale and to analyze the in vitro effects of pesticides (dichlorvos, diazinon, chlorpyrifos, parathion-methyl, temephos, carbaryl, carbofuran, aldicarb, diflubenzuron, novaluron and pyriproxyfen) and metal ions (As³⁺, Cd²⁺, Cu²⁺, Fe²⁺, Mn²⁺, Mg²⁺, K⁺, Pb²⁺, Hg²⁺, Zn²⁺) investigating the potential of this enzyme as environmental biomarker based on current regulations. Specific substrates and inhibitors have indicated AChE to be the predominant cholinesterase (ChE) in the brain of H. littorale. Peak activity was observed at pH 8.0 and 30 °C. The enzymatic activity is otherwise moderately thermostable (≈ 50% activity at 45 °C). The enzyme can reduce the activation energy of acetylthiocholine hydrolysis reaction to 8.34 kcal mol⁻¹ while reaching a rate enhancement of 10⁶. Among the pesticides under study, dichlorvos presented an IC₅₀ value below the maximum concentrations allowed by legislation. This study presents the first report on the inhibition of brain AChE activity from Siluriformes by the pesticides novaluron and pyriproxyfen. Mercury ion also exerted a strong inhibitory effect on its enzymatic activity. The H. littorale enzyme thus has the potential to function as an in vitro biomarker for the presence of the pesticide dichlorvos as well as mercury in areas of mining and industrial discharge.

乙酰胆碱酯酶（AChE; EC 3.1.1.7）是一种丝氨酸水解酶，其主要功能是调节胆碱能突触的神经传递。因此，它是某些农药和重金属的主要目标。它在水生生物中的抑制作用已被用作指示这些污染物在水体中的存在的指标。本研究旨在表征底栖鱼类Hoplosternum littorale中脑AChE的理化和动力学参数，并分析农药（敌敌畏，双嗪农，毒死rif，甲基对硫磷，坦弗非，西维因，甲萘威，呋喃丹，涕灭威，双氟苯隆，去甲灵和吡ip昔芬）和金属离子（As ³⁺，Cd 2 ⁺，Cu 2 ⁺，Fe 2 ⁺，Mn ²⁺，Mg 2 ⁺，K ⁺，Pb 2 ⁺，Hg 2 ⁺，Zn ²⁺）根据当前法规研究该酶作为环境生物标志物的潜力。特定的底物和抑制剂已表明，AChE是滨海假丝酵母脑中的主要胆碱酯酶（ChE）。在pH 8.0和30°C下观察到峰活性。否则，酶的活性是中等稳定的（在45°C时≈50％的活性）。该酶可将乙酰基硫代胆碱水解反应的活化能降低到8.34 kcal mol ^-1，同时提高10 ⁶的速率。在所研究的农药中，敌敌畏具有IC _50值低于法律允许的最大浓度。这项研究提出了第一个关于杀虫剂诺富龙和吡ip昔芬对鸭Sil形脑AChE活性的抑制作用的报告。汞离子也对其酶活性具有很强的抑制作用。在H. littorale因此该酶具有作为农药敌敌畏的存在以及在采矿和工业排放的区域汞的体外生物标记功能的潜力。