Dual Enzyme Activities Assay by Quantitative Electrospray Ionization Quadrupole-Time-of-Flight Mass Spectrometry

Abstract

A practical and rapid method based on electrospray ionization quadrupole-time of flight mass spectrometry (ESI-Q-ToF MS) was developed for detecting activities of both acetylcholinesterase IAChEI and glutathione S-transferase (GST). The simultaneous study of these two enzyme activities is significant for studying human bio-functions, especially for those who take in toxic compounds and have a risk of disease. Here, the enzyme activities were represented by the conversion of enzymatic substrates and determined by quantitatively analyzing enzymatic substrates. Different internal standards were used to quantify each enzymatic substrate and the good linearity of calibration curves demonstrated the feasibility of the internal standards. The Michaelis-Menten constants (Km) of both GST and AChE were measured by this method and were consistent with values previously reported. Furthermore, we applied this approach to detect GST and AChE activities of whole bloods from four deceased and healthy people. The variation in enzyme activity was in accord with information from gas chromatography mass spectrometry [GC/MS). The screening of AChE and GST provided reliable results and strong forensic evidence. This method offers an alternative choice for detecting enzyme activities and is anticipated to have wide applications in pharmaceutical research and prevention in toxic compounds.

Determination of trace chelating carboxylic acids in rice by green extraction combined with liquid chromatography–mass spectrometry analysis and its application in the evaluation of old and new rice

“…LC/MS/MS 30–35 is currently the most sensitive and selective method for detecting organic acids 36–40 . However, CCAs present a class of strongly polar compounds with no UV‐sensitive group in their structure, which is a challenge to analysts 41 .…”

“…However, no relevant investigation on the analysis of CCAs in rice has been reported so far. LC/MS/MS [30][31][32][33][34][35] is currently the most sensitive and selective method for detecting organic acids. [36][37][38][39][40] However, CCAs present a class of strongly polar compounds with no UV-sensitive group in their structure, which is a challenge to analysts.…”