Radioisotope Assay
Radioisotope Assay - Related Videos
01:28
Isotopes and Radioisotopes
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2023
In the early 1900s, English chemist Frederick Soddy realized that an element could have atoms with different masses that were chemically indistinguishable. These different types are called isotopes — atoms of the same element that differ in mass. Isotopes differ in mass because they have different numbers of neutrons but are chemically identical because they have the same number of protons. Soddy was awarded the Nobel Prize in Chemistry in 1921 for this discovery. An isotope containing more...
12:48
Measuring Cation Transport by Na,K- and H,K-ATPase in Xenopus Oocytes by Atomic Absorption Spectrophotometry: An Alternative to Radioisotope Assays
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Cited by 7 •
2013
We describe a method to quantify the activity of K+-countertransporting P-type ATPases by heterologous expression of the enzymes in Xenopus oocytes and measuring Rb+ or Li+ uptake into individual cells by atomic absorption spectrophotometry. The method is a sensitive and safe alternative to radioisotope flux experiments facilitating complex kinetic studies.
06:09
Assaying the Kinase Activity of LRRK2 in vitro
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Cited by 3 •
2012
Leucine Rich Repeat Kinase 2 is a large multidomain kinase, mutations in which are the most common genetic cause of Parkinson's disease. Analysis of the kinase activity of this protein has proven to be a crucial tool in understanding the biology and dysfunction of this protein. In this paper, in vitro assaying of the kinase activity of LRRK2 and a selection of its mutants is described, providing an experimental system to examine phosphorylation of putative substrates and potential dysfunction...
10:34
Essential Metal Uptake in Gram-negative Bacteria: X-ray Fluorescence, Radioisotopes, and Cell Fractionation
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Cited by 4 •
2018
A protocol for the extraction of a periplasmic transition metal chaperone in the context of its native binding partners, and biophysical characterization of its substrate contents by X-ray fluorescence and radiometal uptake is presented.
08:12
The TUNEL Assay
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2023
One of the hallmarks of apoptosis is the nuclear DNA fragmentation by nucleases. These enzymes are activated by caspases, the family of proteins that execute the cell death program. TUNEL assay is a method that takes advantage of this feature to detect apoptotic cells. In this assay, an enzyme called terminal deoxynucleotidyl transferase catalyzes the addition of dUTP nucleotides to the free 3’ ends of fragmented DNA. By using dUTPs that are labeled with chemical tags that can produce...
FAQs
A radioactively labeled substrate, ligand, or antibody participates in a defined reaction or binding event, placing the detectable label at the molecular process being analyzed. The assay then measures emitted radiation and relates that measurement to standards. This design converts an otherwise difficult-to-observe reaction, interaction, or biological quantity into a quantifiable analytical signal.
Separating bound from unbound material clarifies which portion of the radioactive signal is associated with the intended reaction or binding event. Without this distinction, unbound labeled molecules could contribute to the measurement and obscure the target-associated signal. The separation step is therefore central when assays examine ligand binding, antibody interactions, or other selective biological associations.
Standards provide reference measurements against which assay radiation is compared. The resulting comparison allows researchers to calculate the amount of the target rather than merely report that radioactivity was detected. This calibration principle is important for low-concentration measurements, where the assay’s value depends on translating a measured signal into an interpretable quantity.
A radioisotope assay typically begins by combining the radioactive substrate, ligand, or antibody with the biological sample under a defined reaction or binding condition. Researchers then separate bound from unbound material when the assay requires it, measure the emitted radiation, and compare the result with standards. The calculated value can represent enzyme activity, a metabolite-related process, hormone level, or receptor binding.
Radioisotope assays can address several distinct biological questions, including enzyme activity, metabolic flux, hormone levels, and receptor binding. These measurements have supported studies of cell signaling, physiology, and pharmacology. The relevant assay format depends on whether the radioactive component participates in a reaction, tracks a ligand interaction, or enables detection through an antibody.
Because these assays use radioactive materials, work requires controlled handling, appropriate shielding, and radioactive-waste management. These controls are part of the experimental context, not optional details, because the technique depends on maintaining radioactive labels while protecting personnel and the surrounding workspace. Laboratories must therefore integrate measurement procedures with established controls for radioactive materials.