Metabolomics detection

Proteomics and metabolomics detect only a small subset of the total proteome and metabolome, and fluxomics (metabolic flux analysis) tends to focus on discrete pathways determined in part by the substrates that are used for the analysis. To date, gel-based proteomic analysis ranains... 

However, chemical diversity of metabolites requires a variety of detection platforms and presents a unique challenge when one analyzes the metabolome for fingerprinting or... 

In comparison with other measurement methods, NMR has important strengths. Its great virtue is its noninvasive nature, allowing one to obtain spatially resolved metabolic profiles and to investigate metabolomics in vivo. 10 There is little or no sample preparation. It is nondestructive. It is information-rich with regard to the determination of molecular structures because it can detect different chemical groups of metabolites simultaneously. 

Technologies that examine a large number of metabolites at the same time are sometimes known as metabolomics. This term is similar to genomics, in which large numbers of genes are detected or studied simultaneously. Such studies are only in their beginning phases, and researchers do not yet understand if the differences they are finding in metabolites are critical or not. Dopamine and other brain chemicals are important in the development of schizophrenia, at least for some forms of the disease, but scientists do not yet know how. 

Currently, on-line LC-NMR is just at the starting point for dramatic miniaturization and parallelization. Prototypes of NMR probes with remarkable sensitivity values are currently available in 2002, although the ease of operation of the combined separation-detection system is not guaranteed. Because the design of the current analytical LC-NMR probes is so simple, they can be used in many real-world applications. However, current research areas such as proteomics and metabolomics necessitate the utmost sensitivity, using very small amounts of sample, which can only be achieved by employing capillary probes. 

With the use of modem very sensitive analytical methods (especially with the possibility to enhance low-expressed proteins), the concept of substantial equivalence, coined years ago, of GMO to conventional counterparts may not have the same impact as at its origin. With proteomics patterns focusing on low-abundance species, the equivalence may never be demonstrated due to the plasticity of protein expression and their interdependence. It is clear today that the effects of transgenesis on transcriptome do not suffice to predict the modifications in proteomes and consequently in metabolomes (72). Needless to say, with CPLLs, many more modifications would be detected due to the capability to reach very low-expressed proteins. 

Gravett et al. recently published further work that targets some of the areas most amenable to early detection and intervention during pregnancy, labor, and delivery, as a step toward alleviating the disease burden of these illnesses globally (46). Early metabolomic/proteomic evaluation could theoretically lead to a marked reduction in adverse pregnancy outcome. 

Transcriptomic, proteomic, and/or metabolomic approaches have already been shown to be extremely useful to assess food safety and quality at every stage of production to ensure food safety for human consumption. They are also valuable tools to distinguish between similar food products and to detect food frauds (adulteration, origin, authenticity, etc.), food-borne pathogens, toxic species, food allergens, etc. 

The identification of changes in the metabolome can help characterize the biochemical functions of enzymes in the proteome [5, 24]. Not all metabolic changes, however, provide easy readouts. Therefore, more sophisticated analytical methods have been developed to detect and quantify changes in metabolome. The application of modem analytical tools, such as nuclear magnetic resonance (NMR) [19] and mass spectrometry (MS) [5, 24], are the primary tools of metabolomics researchers. In particular, MS has found increased usage as mass spectrometers have improved their sensitivity and mass resolution. 

Fig. I The typical metabolomics workflow has three key steps the isolation of metabolites, detection of the metabolites, and data analysis. The isolation step is typically determined by the class of metabolite being measured because of the physicochemical properties of different metabolite classes (i.e., hydrophobic, hydrophilic), which require different enrichment protocols. Two principle methods for metabolite detection are NMR- and MS-based methods. Finally, the data analysis can be performed in a variety of ways depending on the problem...

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