What are the usages of isotope labeled peptides?

Answer 1

In order to understand the dynamics of molecules in metabolic pathways, it is necessary to establish a method of tracking them. In the past, chemical labeling was the first attempt to this, however, chemical labeling has the disadvantage that the chemical properties of labeled metabolites differ from those of normal metabolites. This problem is solved by using isotopes for labeling metabolites of interest. Isotopes are atoms with the same number of protons but a different number of neutrons in their nuclei. Recall that the chemical properties of an element are a consequence of its electron configuration, which, in turn, is determined by its atomic number, not its Atomic Mass. The metabolic destiny of a specific atom in a metabolite can, therefore, be elucidated by isotopically labeling that position and following its progress through the metabolic pathway.The most common isotopes used in protein research are: 13C and 31P (detected by NMR techniques), and 3H, 14C, and 32P, that emit beta particles and the methods most commonly used in biochemical research for tracking isotopes are: proportional counting (by the use of Geiger counting), liquid scintillation counting, and autoradiography.