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In vivo measurements of control coefficients for hexokinase and glucose‐6‐phosphate dehydrogenase in Xenopus laevis oocytes
Author(s) -
Ureta Tito,
Fernández Waldy Y.,
Centelles Josep J.,
Cascante Marta
Publication year - 2000
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(00)01646-x
Subject(s) - hexokinase , pentose phosphate pathway , glycogen , xenopus , microinjection , dehydrogenase , glucose 6 phosphate dehydrogenase , biochemistry , glycogen synthase , chemistry , pentose , glucose 6 phosphate , phosphate , glycogenesis , glycolysis , enzyme , biology , endocrinology , fermentation , gene
Hexokinase and glucose‐6‐phosphate dehydrogenase activities were increased in Xenopus laevis oocytes by microinjection of commercial pure enzymes. The effect of increased fractional activities on glycogen synthesis or on the production of 14 CO 2 (the oxidative portion of the pentose phosphate pathway) was investigated by microinjection of [1‐ 14 C]glucose and measurements of the radioactivity in glycogen and CO 2 . Control coefficients calculated from the data show that hexokinase plays an important role in the control of glycogen synthesis (control coefficient=0.7) but its influence on the control of the pentose phosphate pathway is almost nil (control coefficient=−0.01). Glucose‐6‐phosphate dehydrogenase injections did not affect the production of 14 CO 2 by the pentose phosphate pathway, indicating that other factors control the operation of this pathway. In addition, an almost null control of this enzyme on glycogen synthesis flux was observed.