Radiochemical Uses

Radium is not the only element to have a radiochemistry related to practical implications. Beryllium is an excellent moderator and therefore has had a long history of use in the nuclear weapon and power industries. Mixed with an alpha-particle source, commonly radium, beryUium also provides a good laboratory source of neutrons, as shown in Equation (13.13)  

It was the successful interpretation of this reaction that led James Chadwick to discover the neutron in 1932. Neutrons produced in this manner were also used in Enrico Fermi s early experiments in uranium fission. 

Strontium-90 is a particularly troublesome fission product due to its (1) long half-life (28.1 years), (2) emission of beta particles [as shown in Equation (13.14)] 

Group 2A metals, magnesium in particular and also calcium, are used as reducing agents to isolate other metals from their halides and oxides. Two representative reactions are given in Equations (13.15) and (13.16)  

Magnesium is also used to isolate aluminum, uranium, zirconium, beryllium, and hafnium, among others. 

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Hence the slope of the plot of log[S] against log[M] must equal Cs-The concentration [S] of unreacted mercaptan regulator may be determined by amperometric titration with silver nitrate,or the combined sulfur in the polymer may be determined radiochemically using mercaptan containing S, and the unreacted mercaptan concentration [S] calculated by difference. Transfer constants for carbon... 

This enzyme is a biotin protein. It also catalyses transcarboxylation reactions. The reaction shown here is an important step in fatty acid synthesis utilising malonyl CoA as an intermediate. It may be assayed radiochemically using C labelled KHCO3 in a reaction which is stopped by the addition of 6 N HCl [180]. 

This is one of the enzymes of the urea cycle. It may be assayed colorimetrically [240] or radiochemically using C labelled L-guanido-arginine [241]. 

This enzyme catalyses one of the reactions involved in the metabolism of catecholamines. It can be assayed radiochemically using C labelled S-adenosylmethionine. The reaction mixture is reacted with dihydroxybenzoic acid and the unused substrate as a benzoate is extracted with organic solvent at acid pH. 

This enzyme catalyses the reaction whereby acetylcholine is synthesised in tissue. It will also react with proprionyl co-enzyme A, but more slowly. It may be assayed radiochemically using C labelled acetyl CoA. Residual acetyl CoA is decomposed by hydroxylamine, and the labelled acetylcholine is precipitated with sodium tetraphenyl-... 

This enzyme catalyses the conversion of dopamine to noradrenaline. It may be assayed radiochemically using H labelled dopamine. 

This is one of the rate-limiting enzymes of glycolysis. It should not be confused with HEXOKINASE E.C. 2.7.1.1 It may be assayed by u.v. absorption using glucose-6-phos-phate dehydrogenase as an indicator (4], or radiochemically using DEAE-cellulose to separate substrate and product (372]. 

This enzyme is a pyridoxal phosphate protein, which catalyses the formation of 7-aminobutyric acid, a possible chemical transmitter in the CNS. It can be used in an indicator reaction for the radiochemical assay of transaminases. It is assayed radiochemically using Clabelled glutamate and COj evolution [391]. 

This enzyme catalyses the second step in the Oxidation of fatty acids. It has been called il-hydroxyacyl dehydrogenase and ketoreductase. The pH optimum for oxidation in vitro is 9.6 to lO.O. At pH 6.0 to 7.0 in vitro it catalyses the reverse reaction. It can be assayed by u.v. spectroscopy [436] or radiochemically using the oxidation of C labelled oleic acid and evolution of C02 [437]. 

This is one of the enzymes involved in serotonin metabolism. Some other hydroxy-indoles react more slowly. It can be assayed radiochemically using C labelled 5-ade-noxylmethionine and chloroform extraction of the methylated product. 

This is the enzyme which catalyses the formation of mevalonate, an important intermediate in the formation of cholesterol from acetyl CoA. It can be assayed radiochemically using C labelled substrate and ether extraction of the product. 

Serum levels of this enzyme increase up to four-fold in acute pancreatitis. It can be estimated by hydrolysis of olive oil emulsion and titration of the liberated fatty acids [479 —480] or radiochemically using triolein labelled with l or C and solvent extraction of the reaction mixture [481-482]. 

This is the enzyme responsible for activating methionine to the 5-adenosyl form in which it acts as a methyl donor. It may be assayed radiochemically using C labelled methionine and product separation using ion exchange. 

This enzyme is a cuproprotein which acts on a variety of primary, secondary, and tertiary amines. It is involved in the metabolism of serotonin, catecholamines, and many other drugs. It may be assayed radiochemically using 0 labelled serotonin, tyramine or dopamine, and solvent extraction of the reaction mixture [508. ... 

ITP can also act as a donor. This enzyme catalyses one of the rate limiting steps of gluconeogenesis. It may be assayed by u.v. spectroscopy using maiate dehydrogenase as an indicator of oxalacetate formation, or radiochemically using the same reactions and measuring C labelled bicarbonate incorporation into maiate [555]. 

This enzyme requires DNA as a primer. It catalyses the reaction responsible for chain lengthening in RNA synthesis. It may be assayed radiochemically using C, H or P labelled nucleotide donors and acid precipitation of the product. 

We measured APRT-activity from erythrocytes lysates of 524 unselected patients of the Medical Policlinic Munich micro-radiochemically using the method of Kelley (1967). Moreover the activity in 127 patients with renal failure on dialysis, and of 41 patients with nephrolithiasis was determined. The family of a patient with low APRT-activity was further investigated. The enzyme of patients with diminished actwity was investigated by measuring heat and cold stability at 55°C and 4 C respectively. 

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