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Interaction of mannose‐6‐phosphate with the hysteretic transition in glucose‐6‐phosphate hydrolysis in intact liver microsomes
Author(s) -
Vidal Hubert,
Berteloot Alfred,
Larue Marie-Josée,
St-Denis Jean-François,
van de Werve Gérald
Publication year - 1992
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 - 10.1016/0014-5793(92)80439-n
Subject(s) - glucose 6 phosphate , phosphate , mannose , microsome , hydrolysis , chemistry , incubation , glucose 6 phosphatase , enzyme , mannose 6 phosphate , substrate (aquarium) , phosphatase , biochemistry , biology , ecology , receptor , growth factor
We showed previously that glucose‐6‐phosphatase activity was characterised in intact liver microsomes by a hysteretic transition between a rapid and a slower catalytic form of the enzyme. We have now further investigated the substrate specificity of these two kinetic forms. It was found that the pre‐incubation of intact microsomes with mannose‐6‐phosphate or glucose‐6‐phosphate (50 μM for 30 s) suppressed the burst in glucose‐6‐phosphatase activity, that the hysteretic transition was reversible and that mannose‐6‐phosphate inhibited glucose‐6‐phosphate hydrolysis during the first seconds of incubation, but not anymore after the burst. Our results indicate (i) that mannose‐6‐phosphate is recognised by the enzyme and can promote the hysteretic transition and (ii) that the transient phase is part of the catalytic mechanism itself.