Thioredoxin reductase and cytoplasmic glutathione peroxidase activity in human foetal and neonatal liver.
Cytosolic thioredoxin reductase (TR) is an FAD-containing homodimeric selenoenzyme which, together with thioredoxin (Trx) and NADPH, forms a powerful oxidoreductase system. Cytoplasmic glutathione peroxidase (GPX-1) is a selenoprotein with antioxidant activity. The TR/Trx system has been associated with cellular processes including regulation of cell growth, and modification of activity of transcription factors. TR may also act as an antioxidant. We have measured TR activity, TR concentration, and GPX-1 activity in human hepatic cytosols from foetuses and neonates. The concentration of TR was significantly greater (P<0.05) in foetal (43.6, 37.9-50.8 microg/g protein, median, interquartile range) than in neonatal liver (11.6, 8.70-15.0 microg/g). This was also true of TR activity which was 2.1, 1.8-2.5 U/g protein in foetal, and 0.65, 0.44-0.74 U/g protein in neonatal liver (P<0.0005). Similarly, GPX-1 activity was significantly higher (P<0.005) in the foetal (199.7, 144.0-227.9 U/g protein) than in neonatal (77.0, 58.4-110.3 U/g protein) hepatic cytosol. Overall, foetal liver expressed approx. 3-fold higher activities of TR and GPX-1 than neonatal liver.
Lewin
M H
MH
Department of Clinical Biochemistry, University of Edinburgh, Royal Infirmary, Edinburgh, UK. mlewin@ed.ac.uk
Hume
R
R
Howie
A F
AF
Richard
K
K
Arthur
J R
JR
Nicol
F
F
Walker
S W
SW
Beckett
G J
GJ
D001344:Autopsy; D003593:Cytoplasm / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D005865:Gestational Age; D005979:Glutathione Peroxidase / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D008099:Liver / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development; D018384:Oxidative Stress; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism*
D005979:Glutathione Peroxidase; D013880:Thioredoxin-Disulfide Reductase