Phosphorus, radioactive, production

This experiment is usually run using [3H]ethanol and locating the radioactive product by thin-layer chromatography. An alternative method would be to label the cells with [3H]oleic acid and [32P]phosphate and then monitor the ratio of the tritium label to phosphorus-32 label in any detectable phosphatidic acid and compare to the parent phosphoglycerides. The ratio would not change if the phosphatidic acid were derived by action of phospholipase D in the stimulated cells. However, the assay of choice at the present time is that associated with the formation of phosphatidylethanol. 

The product, phosphorus-30, is radioactive, decaying by positron emission ... 

Reference has repeatedly been made to the powerful anticholinesterase activity of D.F.P. (p. 61). Towards pseudocholinesterase, for example, it is effective in concentration as low as 10 11M. In order to throw light on its mode of action with esterases,3 radioactive D.F.P. containing 32P was prepared.4 An account of its production on what may be conveniently called the one-gram scale , directly from phosphorus, is given below. 

When compound (VII) was heated to 130° for 2-5 hr. it isomerized to OO -diethyl S-ethylmercaptoethyl phosphoro-thiolate (VIII). This was shown by successive partitioning of the heated product between suitable solvents, the partition ratios of the radioactive phosphorus being determined after each extraction. If only one compound is present all the ratios would be the same if two or more compounds are present, the observed over-all partition ratios would change in systematic fashion. 

Crystallisation was one of the earliest methods used for separation of radioactive microcomponents from a mass of inert material. Uranium X, a thorium isotope, is readily concentrated in good yield in the mother liquors of crystallisation of uranyl nitrate (11), (33), (108). A similar method has been used to separate sulphur-35 [produced by the (n, p) reaction on chlorine-35] from pile irradiated sodium ot potassium chloride (54), (133). Advantage is taken of the low solubility of the target materials in concentrated ice-cold hydrochloric acid, when the sulphur-35 as sulphate remains in the mother-liquors. Subsequent purification of the sulphur-35 from small amounts of phosphorus-32 produced by the (n, a) reaction on the chlorine is, of course, required. Other examples are the precipitation of barium chloride containing barium-1 from concentrated hydrochloric acid solution, leaving the daughter product, carrier-free caesium-131, in solution (21) and a similar separation of calcium-45 from added barium carrier has been used (60). 

For determination of total P-phosphorus incorporation, filter the precipitate over a glass fiber filter and count for radioactivity. If electrophoresis is intended, collect the precipitate by centrifugation with 5000 X g and dissolve the pellet in the appropriate sample buffer. Choose the electrophoresis system with respect to the different pH stability of phosphorylation products. 

The first of these equations shows that the result of the nuclear reaction in which aluminum is bombarded with or-partides is the emission of a neutron and the production of a radioactive isotope of phosphorus. The second equation shows the radioactive disintegrations of the latter to yield a stable silicon atom and a positron. Continuation of this line of investigation by several research groups confirmed that radioactive nuclides are formed m many nuclear reactions. 

Sometimes the nucleus can be changed by bombarding it with another type of particle. This is referred to as induced radioactivity. In 1934, Irene Curie, the daughter of Pierre and Marie Curie, and her husband, Frederic Joliot, announced the first synthesis of an artificial radioactive isotope. They bombarded a thin piece of aluminum foil with ot-particles produced by the decay of polonium and found that the aluminum target became radioactive. Chemical analysis showed that the product of this reaction was an isotope of phosphorus. 

The product of this reaction, P °, was the first man-made radioactive isotope reported and also the first positron emitter. By tracing the radiations, it could be shown that the positron-emitter produced in the reaction had the chemistry of phosphorus. In this case, then, the heavier product could be identified by its chemistry even though only very tiny amounts were formed. 

As another example, the production of radioactive phosphorus, P"-, by bombardment of ordinary phosphorus, P with 10-million volt deuterons from a cyclotron may be mentioned. The reaction is... 

Whether the mechanism requiring activation of a carboxylate ion by ATP involves attack of the carboxylate ion on the a-phosphorus or the 8-phosphorus of ATP cannot be determined from the reaction products because AMP and pyrophosphate are obtained as products in both mechanisms. The mechanisms, however, can be distinguished by a labeling experiment in which the enzyme, the carboxylate ion, ATP, and radioactively labeled pyrophosphate are incubated, and the ATP is isolated. If the isolated ATP is radioactive, the mechanism involves attack on the a-phosphorus. If it is not radioactive, the mechanism involves attack... 

Radioactive isotopes for tracer studies may be prepared artificially from nonradioactive elements by bombarding them with suitable nuclear particles produced in a cyclotron or a nuclear reactor. The discovery of this effect was made in 1934 by the French physicists Irene Joliot-Curie (1897-1956) and her husband Frederic Joliot-Curie (1900-1958). They were studying the effect of bombarding light elements such as aluminum with alpha (a) particles, which are beams of helium nuclei, fHe. They noticed that, after the bombardment had ceased, a new form of radiation continued to be emitted, and they concluded that a new isotope had been formed. In the case of the bombardment of ordinary aluminum, HAl, with a particles, the product is an isotopic form of phosphorus, ifP, the most abundant isotope of phosphorus being f P. The process is... 

Radioactive elements, especially carbon-14, were key products of the Manhattan Project, and could be produced in large quantities by the nuclear reactors. They would provide the world with new tools for chemical and biomedical research. Radioactive tracers were able to broadcast their presence as part of radiolabeled molecules as they defined the the stream of life. Being able to measure the chemical processes in every part of the body of living organisms made it possible for creative biological and medical scientists to provide a whole new approach to biochemistry and medicine. The radionuclides, chiefly carbon-14 and phosphorus-32, led the way. 

The transfer of the N-acetylmuramyl pentapeptide to phospholipid is reversible and generates a pyrophosphoryl linkage, with one phosphorus atom derived from the lipid and one from the UDP group. That this is so was shown by radioactive labelling of the starting materials and degradation of the product. 

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