Isotopic labeling (or isotopic labelling) is a technique used to track the passage of an isotope, or an atom with a variation, through a reaction, metabolic pathway, or cell. The reactant is 'labeled' by replacing specific atoms by their isotope. The reactant is then allowed to undergo the reaction. The position of the isotopes in the products is measured to determine the sequence the isotopic atom followed in the reaction or the cell's metabolic pathway.
In isotopic labeling, there are multiple ways to detect the presence of labeling isotopes; through their mass, vibrational mode, or radioactive decay. Mass spectrometry or nuclear magnetic resonance detects the difference in an isotope's mass, while Infrared spectroscopy detects the difference in the isotope's vibrational modes. The radioactive decay can be detected through an ionization chamber or autoradiographs of gels.
An example of the use of isotopic labeling is the study of phenol (C6H5OH) in water by replacing common hydrogen (protium) with deuterium (deuterium labeling). Upon adding phenol to deuterated water (water containing D2O in addition to the usual H2O), the substitution of deuterium for the hydrogen is observed in phenol's hydroxyl group (resulting in C6H5OD), indicating that phenol readily undergoes hydrogen-exchange reactions with water. Only the hydroxyl group was affected, indicating that the other 5 hydrogen atoms did not participate in these exchange reactions.
Other articles related to "isotopic labeling":
... Chemical synthesis Enzyme-mediated exchange Recombinant protein expression in isotopic labeled media. ...
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