Dual-Channel Enzymatic Inhibition Measurement (DEIM) Coupling Isotope Substrate via Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry
作者:Min Tao、Li Zhang、Yinlong Guo
DOI:10.1007/s13361-018-2054-3
日期:2018.12.1
A novel dual-channel enzymatic inhibition measurement (DEIM) method was developed to improve the repeatability with light/heavy isotope substrates, producing reliable relative standard deviations (< 3%) by employing acetylcholinesterase (AChE) as the model enzyme. The matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) was adapted for enzyme-inhibited method due to its good salt-tolerance and high throughput; meanwhile, dual-channel enzymatic reactions were performed to improve the repeatability of each well. The acetylcholinesterase inhibition measurement was conducted by mixing the quenched enzyme reaction solution of blank group (with heavy isotope as substrate) and experimental group (with light isotope as substrate), of which the inhibition rate might be affected by isotope effects. Hence, inverse study and Km measurement were implemented to validate the method. The inverse study shows similar inhibition rate (68.9 and 70.3%) and the Km of isotope substrates are analogous (0.139 and 0.135 mM), which demonstrated that the novel method is feasible to AChE inhibition measurement. Finally, the method was applied to herb extracts, half of which exhibit inhibition to AChE. The precise dual-channel enzymatic inhibition measurement (DEIM) method could be regarded as a promising approach to potential enzyme inhibitor screening.
以乙酰胆碱酯酶(AChE)为模型酶,建立了一种新型的双通道酶抑制测量(DEIM)方法,以提高轻/重同位素底物的重复性,产生可靠的相对标准偏差(< 3%)。由于基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)具有良好的耐盐性和高通量,因此被用于酶抑制方法;同时,双通道酶反应提高了每孔的重复性。乙酰胆碱酯酶抑制率的测定是将空白组(以重同位素为底物)和实验组(以轻同位素为底物)的淬火酶反应液混合后进行的,其中抑制率可能会受到同位素效应的影响。因此,我们采用了反演研究和 Km 测量来验证该方法。反向研究表明,抑制率相似(68.9%和 70.3%),同位素底物的 Km 值相似(0.139 和 0.135 mM),这表明新方法在 AChE 抑制测定中是可行的。最后,该方法被应用于草药提取物,其中一半对 AChE 有抑制作用。精确的双通道酶抑制测量(DEIM)方法可被视为筛选潜在酶抑制剂的一种有前途的方法。
Assessment of false transmitters as treatments for nerve agent poisoning
作者:Charlotte Whitmore、Christopher D. Lindsay、Mike Bird、Samuel J. Gore、Helen Rice、Rebecca L. Williams、Christopher M. Timperley、A. Christopher Green
DOI:10.1016/j.toxlet.2019.12.010
日期:2020.3
cholinergic synapses. Current post-exposure nerve agent treatment includes atropine to treat overstimulation at muscarinic synapses, a benzodiazepine anti-convulsant, and an oxime to restore the function of AChE. Aside from the oxime, the components do not act directly to reduce the overstimulation at nicotinic synapses. The false transmitters acetylmonoethylcholine (AMECh) and acetyldiethylcholine (ADECh)