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- Guthenberg, Claes, 1950-
(författare)
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Isolation and characterization of glutathione S-transferases from various animal sources
- 1981
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the present investigation several forms of glutathione S-transferase were found in preparations of rat liver, rat lung, adult human liver, fetal human liver and whole earthworms. Human placenta, however, appeared to contain only one form of glutathione S-transferase. This multiplicity of glutathione S-transferase resembles the multiplicity of other drug-metabolizing enzymes. Three forms of glutathione S-transferase, denoted as transferases A, B and C, were purified from rat liver by ion-exchange chromatography, gel filtration and chromatography on hydroxyapatite. The molecular weights, subunit composition, isoelectric points and the substrate specificity of these enzymes were determined. Transferases A and C are dependent on free SH groups for their activity. The glutathione S-transferase acitivity in rat liver cytosol increased 2-3 fold after induction with methylcholanthrene or phenobarbital. Treatment with trans-stilbene oxide results in a 3-4 fold increase in this activity. With trans-stilbene oxide it was demonstrated that the acitivity of glutathione S-transferases A, B and C all increased in comparison to control rats. Quantitative immunoelectrophoresis revealed that this induction also increased the amount of these enzyme proteins. In addition, rat lung contained transferases A, B and C and an additional, previously unknown glutathione S-transferase which was isolated from this tissue. This enzyme is not present in the liver. The glutathione S-transferase from human placenta was purified to homogeneity. The most efficient purification step was affinity chromatography on hexylglutathione coupled to epoxy-activated Sepharose 6B. A new form of human glutathione S-transferase was found in liver preparations from certain individuals. This new enzyme, denoted transferase /x, was also purified to homogeneity by a procedure including affinity chromatography on a gel consisting of hexylglutathione bound to epoxy-activated Sepharose 6B. This new transferase is not present in fetal liver. The enzymes isolated from human placenta and adult human liver were characterized in terms of isoelectric points, molecular weights, subunit composition and substrate specificity. The most remarkable property observed 'is in the relatively high activity of transferase fi. with the extremly mutagenic substance benzo (a) pyrene-4,5-oxide. This finding suggests that this new enzyme may be of great importance in the detoxication of metabolites of carcinogenic polycyclic hydrocarbons.
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| 2. |
- Myrelid, Åsa, 1974-, et al.
(författare)
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Increased neonatal thyrotropin in Down syndrome
- 2009
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Ingår i: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 98:6, s. 1010-1013
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Tidskriftsartikel (refereegranskat)abstract
- AIM: Down syndrome (DS) is frequently associated with thyroid dysfunction. The aim of this study was to investigate the blood concentration of thyrotropin (TSH) observed at neonatal screening of infants with DS and its possible association with development of hypothyroidism during childhood. METHODS: TSH levels from neonatal screening of 73 children (34 F) with DS born in 1986-1996 were studied retrospectively and compared with those of controls. The DS children were followed up regarding thyroid function to the age of 10 years in this descriptive study. RESULTS: The DS infants had a higher mean TSH level and a higher TSH standard deviation score (SDS) than controls (7.0 +/- 7.45 mU/L vs. 3.9 +/- 2.43 mU/L and 1.1 +/- 2.67 vs. 0, respectively). The differences were mainly attributable to higher values in the male DS children. The TSH level at screening did not predict thyroid dysfunction during childhood. CONCLUSION: Infants with DS, especially boys, showed elevated levels of TSH at neonatal screening, indicating the occurrence of mild hypothyroidism already in early life. The TSH levels could not predict development of manifest thyroid disease later in childhood.
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| 3. |
- Ålin, Per, et al.
(författare)
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Purification of major basic glutathione transferase isoenzymes from rat liver by use of affinity chromatography and fast protein liquid chromatofocusing
- 1985
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 146:2, s. 313-320
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Tidskriftsartikel (refereegranskat)abstract
- Seven major isoenzymes of glutahione transferase with isoelectric points ranging from pH 6.9 to 10 were isolated from rat liver cytosol. The purification procedure included affinity chromatography on immobilized S-hexylglutathione followed by high-performance liquid chromatofocusing. Characteristics, such as physical properties, reactions with antibodies, specific activities with various substrates, kinetic constants, and sensivities to a set of inhibitors, are given for discrimination and identification of the different isoenzymes. The multiple forms of the enzyme correspond to glutathione transferases 1-1, 1-2, 2-2, 3-3, 3-4, and 4-4 in the recently introduced nomenclature [W. B. Jakoby et al. (1984) Biochem. Pharmacol. 33, 2539–2540]. A seventh form appears to be a heterodimeric protein composed of subunit 3 and an as yet unidentified subunit.
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