Iodometric Determination of Peroxygen in Organic Compounds

Kokatnur, V. R.; Jelling, Murray

doi:10.1021/ja01850a082

Cited by 162 publications

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“…Plasma and erythrocyte glutathione was measured by DTNB glutathione reductase method [22]. Plasma and erythrocyte glutathione peroxidase was measured by the method of Kokatnur and Jelling [23]. Erythrocyte glutathione reductase was analyzed by Beutler's method [24] and erythrocyte glutathione S-transferase was assayed by the method of Habig et al [25].…”

Section: Methodsmentioning

confidence: 99%

β-Carotene affects antioxidant status in non-insulin-dependent diabetes mellitus

Levy

Ben‐Amotz

et al. 1999

Pathophysiology

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Section: Methodsmentioning

confidence: 99%

β-Carotene affects antioxidant status in non-insulin-dependent diabetes mellitus

Levy

Ben‐Amotz

et al. 1999

Pathophysiology

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“…(Kokatnur & Jelling, 1941). The enzyme assay with H202 as substrate was performed by the method of Beutler (1971).…”

Section: Methodsmentioning

confidence: 99%

Purification and properties of glutathione peroxidase from human placenta

Awasthi¹,

Dao²,

Lal³

et al. 1979

Biochemical Journal

104

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Glutathione peroxidase (glutathione-H2O2 oxidoreductase; EC 1.11.1.9) was purified to homogeneity from human placenta by using (NH4)2SO4 precipitation, ion-exchange chromatography, Sephadex gel filtration and preparative polyacrylamide-disc-gel electrophoresis. Glutathione peroxidase from human placenta is a tetramer, having 4g-atoms of selenium/mol of protein. The molecular weight of the enzyme is about 85 000 with a subunit size of about 22000. Kinetic properties of the enzyme are described. On incubation with cyanide, glutathione peroxidase is completely and irreversibly inactivated and selenium is released as a low-molecular-weight fragment. Reduced glutathione, f,-mercaptoethanol and dithiothreitol protect the enzyme from inactivation by cyanide and the release of selenium. Properties of human placental glutathione peroxidase are similar to those of isoenzyme A reported earlier by us from human erythrocytes. The presence of isoenzyme B, reported earlier by us in human erythrocytes, was not detected in placenta. Also selenium-independent glutathione peroxidase (isoenzyme II), which is specific for cumene hydroperoxide, was not present in human placenta.

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“…The rate of reaction was measured by following the decrease in A340 corresponding to the oxidation of NADPH in a Gilford model 2400-2 spectrophotometer at 370C. The iodometric titration by the method of Kokatnur & Jelling (1941) was used to determine the exact concentrations of the stock solutions of t-butyl hydroperoxide and cumene hydroperoxide. To study the inhibition of GSH peroxidase activity by cyanide, 'the enzyme was incubated at 40C for 30min with 3323 mM-KCN.…”

mentioning

confidence: 99%

Interrelationship between anionic and cationic forms of glutathione S-transferases of human liver

Awasthi¹,

Dao²,

Saneto³

1980

Biochemical Journal

199

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Human liver glutathione S-transferases (GSH S-transferases) were fractionated into cationic and anionic proteins. During fractionation with (NH4)2SO4 the anionic GSH S-transferases are concentrated in the 65%-saturated-(NH4)2SO4 fraction, whereas the cationic GSH S-transferases separate in the 80%-saturated-(NH4)2SO4 fraction. From the 65%-saturated-(NH4)2SO4 fraction two new anionic GSH S-transferases, ct and y/, were purified to homogeneity by using ion-exchange chromatography on DEAEcellulose, Sephadex G-200 gel filtration, affinity chromatography on GSH bound to epoxy-activated Sepharose and isoelectric focusing. By a similar procedure, cationic GSH S-transferases were purified from the 80%-saturated-(NH4)2SO4 fraction. Isoelectric points of GSH S-transferases co and ,v are 4.6 and 5.4 respectively. GSH S-transferase co is the major anionic GSH S-transferase of human liver, whereas GSH S-transferase yv is present only in traces. The subunit mol.wt. of GSH S-transferase co is about 22 500, whereas that of cationic GSH S-transferases is about 24 500. Kinetic and structural properties as well as the amino acid composition of GSH S-transferase co are described. The antibodies raised against cationic GSH S-transferases cross-react with GSH S-transferase co. There are significant differences between the catalytic properties of GSH S-transferase co and the cationic GSH S-transferases. GSH peroxidase II activity is displayed by all five cationic GSH S-transferases, whereas both anionic GSH S-transferases do not display this activity.

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Iodometric Determination of Peroxygen in Organic Compounds

Cited by 162 publications

References 0 publications

β-Carotene affects antioxidant status in non-insulin-dependent diabetes mellitus

β-Carotene affects antioxidant status in non-insulin-dependent diabetes mellitus

Purification and properties of glutathione peroxidase from human placenta

Interrelationship between anionic and cationic forms of glutathione S-transferases of human liver

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