Metabolites classes

RACs. The LOD and LOQ for each study should be determined. Until each study s LOD and LOQ have been determined, use the lower limit of method validation (LLMV) of 0.01 mgkg for each metabolite class as the reference LOQ. LLMV is defined as the lowest level of fortification where we have demonstrated acceptable recovery and precision of EMA- and HEMA-producing metabolites. 

Figure 3.3 GC/MS metabolic profiles of a polar M. truncatula root extract that illustrates the elution regions of various metabolite classes. The (a) normalized chromatogram is dominated by several peaks, but the (b) expanded view of the same root profile reveals a substantially larger amount of information not apparent at first glance.

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...

NMR spectroscopy is in many respects an ideal analytical technology for metabolic profiling because it is equally sensitive to all metabolites, it can provide quantitative results, direct analysis, metabolite identification, and broad metabolite class coverage. However, NMR spectroscopy gives information only for the abundant metabolites (due to the method s relatively poor... 

Fig. 2. Dependence of rate of in vivo metabolism on tissue concentration for benz[a]anthracene (BaA) in whole Nereis virens [calculated from 4- to 6-day exposure data of Table 4.2 of McElroy (1985c) and from McElroy (1985a)]. Tissue BaA concentration is the sum of parent compound and all metabolite classes. In vivo rates include radiolabel incorporated into the macromolecular (non-extractable) fraction (rates excluding this fraction are 0.04 to 0.2 pmol min wet wt.). The equation of the regression is given by rate (in pmol min g ) = 0.038 + 0.077 [tissue cone, (in nmolg )] correlation coefficient = 0.949 (n = 4)...

MS/MS is clearly a versatile instrument in that it can measure different metabolite classes in a single assay, that is, ACs and amino acids. Structurally similar compounds that may also be analyzed include thyroxine (T4). Thyroxine is derived from Tyr and is an iodinated hormone. Due to the fact that T4 retains the alpha amino groups, it can also be detected as an NL of 102 for the butyl ester. This recently published assay [22] has yet to be widely used in part because metabolite is present in very low concentrations (more than 100-fold less than some amino acids), and the disorder screened... 

Lichen species Metabolite Class of compound Production pathways" Category of use References... 

Examples of Integrative Approaches to Study Specific Metabolite Classes in Model Plant Systems... 

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