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Gulonolactone oxidase activity‐dependent intravesicular glutathione oxidation in rat liver microsomes
Author(s) -
Puskás Ferenc,
Braun László,
Csala Miklós,
Kardon Tamás,
Marcolongo Paola,
Benedetti Angelo,
Mandl József,
Bánhegyi Gábor
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00678-4
Subject(s) - chemistry , microsome , glutathione , biochemistry , endoplasmic reticulum , oxidase test , enzyme , alamethicin , vesicle , membrane , lipid bilayer
The orientation of gulonolactone oxidase activity was investigated in rat liver microsomes. Ascorbate formation upon gulonolactone addition resulted in higher intravesicular than extravesicular ascorbate concentrations in native microsomal vesicles. The intraluminal ascorbate accumulation could be prevented or the accumulated ascorbate could be released by permeabilising the vesicles with the pore‐forming alamethicin. The formation of the other product of the enzyme, hydrogen peroxide caused the preferential oxidation of intraluminal glutathione in glutathione‐loaded microsomes. In conclusion, these results suggest that the orientation of the active site of gulonolactone oxidase is intraluminal and/or the enzyme releases its products towards the lumen of the endoplasmic reticulum.