Enzymatic analysis glutamate

This compound was isolated from seeds of Allium schoenoprasum. The structure was established by enzymatic hydrolysis to give L-glutamic acid, S-(prop-l-enyl)-cysteine and S-(prop-l-enyl)-cysteine sulphoxide, determination of the N-terminal by dinitrophenylation and determination of the C-terminal by enzymatic treatment with carboxypeptidase A, which only hydrolyzes normal peptide bonds and therefore gave rise to S-(prop-l-enyl)-cysteine sulphoxide and y-glutamyl-S-(prop-l-enyl)-cys-teine. The L-configuration of the S-(prop-l-enyl)-cysteine sulphoxide was established by enzymatic analysis (215). 

An excellent review on protein hydrolysis for amino acid composition analysis has been published by Eountoulakis and Lahm [190], Hydrolysis can be performed by either chemical (under either acidic or basic conditions) or enzymatic means. The acidic hydrolysis itself can be carried out in a liquid or a gas-phase mode. The conventional acid hydrolysis uses 6M HCl for 20-24 h at 110°C under vacuum [200], In these conditions, asparagine and glutamine are completely hydrolyzed to aspartic acid and glutamic acid, respectively. Tryptophan is completely destroyed (particularly in the presence of high concentrations of carbohydrate), while cysteine and sometimes methionine are partially oxidized. Tyrosine, serine, and threonine are partially destroyed or hydrolyzed and correction factors have to be applied for precise quantification [190,201],... 

Many enzymatic assays have also been developed for the analysis of proteolytic products. Total amino acids in Cheddar cheese were determined by Puchades et al. (1990) using the L-amino acid oxidase enzyme. Glutamic acid has been quantified by flow injection analysis using glutamate dehydrogenase (Puchades et al., 1989) and using the Boehringer-Mannheim kit (McSweeney et al., 1993). 

In the field of food analysis, milk was the real matrix in which several metabolites have been analysed by the use of the microdialysis sampling technique. Acetylcholine, glucose and glutamate were analysed by Yao et al. [189], coupling a microdialysis probe with an on-hne enzymatic reactor and a Pt electrode coated with a 1,2-diaminobenzene polymer. 

This compound is unstable and has not been isolated in a pure state directly from naturally-occurring material. The structure determination was carried out on material produced by enzymatic oxidation of N -(4-hydroxyphenyl)-L-glutamine and was based on elementary analysis, UV-spectroscopy, IR-spectroscopy of two acetylated derivatives, and acid hydrolysis to give glutamic acid (369). 

Near-infrared spectroscopy (NIR), which is a nondestructive analytical technique, has been employed for the simultaneous prediction of the concentrations of several substrates, products, and constituents in the mixture sampled from fermentation process. In this chapter, applications of NIR to monitoring of the various fermentation processes are introduced. The fermentation processes mentioned here are wine, beer, Japanese sake, miso (soybean paste), soy sauce, rice vinegar, alcohol, lactic acid, glutamic acid, mushroom, enzymatic saccharification, biosurfactant, penicillin, and compost. The analysis of molasses, which is a raw material of fermentation, with NIR is also introduced. These studies indicate that NIR is a useful method for monitoring and control of fermentation process. 

In 1998, Mizutani et al. developed a flow injection analysis (FIA) system with a GIOD enzyme/polyion complex bilayer membrane-based electrode as a detector to determine L-glutamic acid [16]. The authors remark that the bilayer membrane is better than the others, because the analyte permeates freely to the layer and undergoes the enzymatic reaction, whereas the permeation of the interferents is strongly restricted. To form the bilayer membrane for L-glutamic acid determination, the authors used a gold electrode with a suitable treatment to modify it. The most important steps are ... 

Khampha W., J. Yakovleva, D. Isarangkul et al. 2004. Specific detection of L-glutamate in food using flow-injection analysis and enzymatic recycling of substrate. Anal. Chim. Acta 518 127-135. 

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