Quantitative proteomics is a powerful approach used for both discovery and targeted proteomic analyses to understand global proteomic dynamics in a cell, tissue or organism. Most quantitative proteomic analyses entail the isotopic labeling of proteins or peptides in the experimental groups, which can then be differentiated by mass spectrometry. Relative quantitation methods (SILAC, ICAT, ICPL and isobaric tags) are used to compare protein or peptide abundance between samples, while spiking unlabeled samples with known concentrations of isotopically-labeled synthetic peptides can yield absolute quantitation of target peptides via selected reaction monitoring (SRM). Label-free strategies are also available for both relative and absolute quantitation. Although these strategies are more complex than mere protein identification, quantitative proteomics is critical for our understanding of global protein expression and modifications underlying the molecular mechanisms of biological processes and disease states.
The limit of quantitation differs from the limit of detection in that the limit of detection describes the smallest concentration of a drug analyte that can be observed, whereas the limit of quantitation describes the smallest concentration of a drug analyte that not only can be observed, but can also be observed and measured with consistent accuracy, without being subject to imprecision or bias. Never heard of 'quantisation' in qPCR in a meaning like 'mRNA quantification'. Quantisation as defined on Wikipedia seems like something different than counting the number of template molecules, which is what qPCR is for. Quantisation as I learned is a process of simplyfing some values, like an image of sound compression, so unless it was used in this meaning, I don't think it's used right.
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