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In vivo measurements of control coefficients for hexokinase and glucose-6-phosphate dehydrogenase in Xenopus laevis oocytes.

Authors
  • Ureta, T
  • Fernández, W Y
  • Centelles, J J
  • Cascante, M
Type
Published Article
Journal
FEBS Letters
Publisher
Wiley (John Wiley & Sons)
Publication Date
Jun 16, 2000
Volume
475
Issue
2
Pages
145–149
Identifiers
PMID: 10858506
Source
Medline
License
Unknown

Abstract

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 14CO(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 14CO(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.

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