The research group of Maolan group, Institute of chemistry, Chinese Academy of Sciences has made new progress in the study of bioelectrochemistry of glutamate synthetase

Chemical signal transmission is the basis of all life activities Quantitative acquisition of chemical signals in vivo is of great significance to the understanding of nervous system activities However, the diversity and variability of the chemical environment of the nervous system make the study of in vivo analytical chemistry extremely difficult With the support of NSFC, the Ministry of science and technology and the Chinese Academy of Sciences, the research group of Maolan group, Institute of chemistry, Chinese Academy of Sciences, has been engaged in basic and applied research in this field for a long time Based on the principle of electrochemistry, a series of electrochemistry analysis principles and methods with high selection, high sensitivity and space-time resolution for important small neuromolecules have been developed In recent years, the research group has focused on the development of in vivo electroanalytical chemistry based on the principle of bioelectrochemistry Generally speaking, the performance of bioelectrochemical analysis (such as sensitivity, anti-interference ability, etc.) depends on the electron transfer process between enzyme and electrode interface Through efforts, the researchers found that by using the surface wetting effect of common organic solvent small molecules and regulating the interaction between enzyme and electrode, the orientation of enzyme molecules on the surface of carbon nanotubes can be optimized, and then the direct electron transfer of enzyme molecules can be promoted, which effectively promotes the electrochemical catalysis of biological products Because the common enzyme elements (oxidase or dehydrogenase) need oxygen or coenzyme to participate in the bioelectrochemical catalysis, the existing enzyme based bioelectrochemical sensors are difficult to be applied to in vivo analysis The effective way to solve this problem is to find or design new enzyme recognition elements Recently, for the in vivo analysis of glutamate, an important neurotransmitter, researchers have constructed a bioelectrochemical sensing interface with glutamate synthetase as the recognition element This enzyme catalyzes the synthesis of glutamate in natural state, but how to use this enzyme to carry out in vivo electroanalytical chemistry has not been reported The researchers found that the introduction of a suitable electron transfer mediator between the enzyme and the electrode can effectively regulate the direction of its electrocatalysis Specifically, the introduction of methyl viologen with low mode potential at the interface can realize the enzyme catalyzed electrosynthesis from ketoglutarate and glutamine to glutamic acid, while the introduction of potassium ferricyanide with high mode potential can reverse the reaction direction, realize the enzyme catalyzed electrochemical oxidation of glutamic acid, and the catalytic current has a good correlation with the concentration of glutamic acid It is further revealed that, unlike the oxidase and dehydrogenase sensors, the glutamate synthetase based sensors not only have high sensitivity, but also are not affected by the change of oxygen concentration This work provides a new way for electrochemical analysis in vivo The results were published in J am Chem SOC (DOI: 10.1021 / JACS 8b08020).