|
Metabolome can bedescribed as the terminal output of the genome that comprises the overallcomplement of metabolites (molecules with low molecular weight) in an organismor cell. The technique of measuring molecules is divided into two groups:targeted metabolomics and untargeted metabolomics. The wide range measuring ofknown metabolite molecules in a disease state or in physiological stimuli iscalled targeted metabolomics. Understandingtargeted metabolomics Targeted metabolomics is aquantitative approach where a group of metabolites are quantitated with thehelp of 15N or 13C (internal or external) compounds that are known as labeledisotopes. Additionally, with the internal standard help, the analysis can bedone by semi-quantitative or quantitative methods. This method of analyzationhelps in the overall understanding of the massive array of metabolites in theend products (like sweat, urine, etc.) in addition to its kinetics. And, toattribute the known pathways of biochemicals that they subsidize, statisticalanalysis uses this data (outcome) as the input variable. The core panel of themetabolomics comprises several metabolites such as organic acids, drugs,neuromodulators, and byproducts of intermediary metabolism that happen within acell. These panels are known components that are used by investigators in theircase analysis. Making use of thistargeted metabolomics, the sample preparation is optimized. This restricts thedominance of the molecules of high-abundance in the analyses. Characteristicsof targeted metabolomics As mentioned above, therole of targeted metabolomics is to evaluate the set of interpreted andbiochemical metabolites. This type of restricted coverage of metabolomeproves that the targeted metabolomics rely on metabolites and their biochemicalpathways. This makes the discovery of metabolic perturbations complicated.Moreover, with the usage of labelled standards, the targeted metabolomics arequantitative. This creates a platform toestablish the clear exhibition of physiological processes. The perfectexplanation of metabolites in the species minimizes the prospects of analyticalartifacts to ensure the data analysis. Targeted metabolomics is also capable ofproducing specialized extraction techniques. Factorsinvolved in targeted metabolomics 1. Metaboliteextraction Sample preparation throughmetabolite extraction is the most essential process whose outcome in the properquantification of the targeted metabolites. As far as untargeted metabolomicsis considered, the method of extraction should release the wide range ofmetabolites through the sample. Whereas in targeted metabolomics, there areonly a few metabolites analyzed. The focus of this method should be on thestreamline extraction of the needed metabolites. Hence, the method ofextraction is customized to the relative abundance and physicochemicalattributes of a metabolite subset that is to be analyzed. When the exclusion ofcomponents takes place, the metabolites and proteins are not intentional forthe analysis. A range of factors is considered in the extraction process. Theyare liquid–liquid, biphasic or monophasic in nature, pH, temperature and theratio of aqueous and organic solvents. The metabolite extractionis capable of affecting the productivity of the examination and the nature andthe quantity of the extracted metabolites, if any disruption occurs. 2. Liquidchromatography–mass spectrometry (LC-MS) Every single metabolitehas its own unique ions that undergo specific transition processes. With thehelp of these transition states, the uniqueness of the metabolite will beascertained if combined with a chromatographic retention. Hence, all the retentiontimes, transitions, collision, and concentration range for the metabolite canbe derived with the help of targeted metabolomics. The LC-MS methods ofanalyzation with targeted metabolomics are known to produce the result of boththe ionization (positive and negative). There are severalconsiderations taken into account when experimenting with LC-MS in targetedmetabolomics. It sometimes affects the experimented quality of the data.Therefore, opting for the exact ionization parameters is essential. The Electrosprayionization (ESI) is known as the most common and efficient method of ionizationperformed in LC-MS-related experiments. This ionization process is also calledas the technique of soft ionization. The chemical derivatizations are not requiredin ESI technique to improve the volatility. It also helps in reducing thefragmentation that helps in the analytical interpretation.
Advantagesof targeted metabolomics The MS-based metabolomicsis difficult to identify as the retention time of the chromatographic and ionintensities undergo a temporal drift. Due to this, the demo analysis for thestudy must be done in a variable manner and on the same day and batch the datamust be acquired. This in return minimizes the variations that occur inthe sets. The targeted metabolomicsplays a two-fold aspect in this analysis:
参考材料：
|
|
|
