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

FEBS Letters

Ureta, Tito¹  Centelles, Josep J.²  Cascante, Marta²  Fernández, Waldy Y.² 

[1] Departamento de Biologı́a, Facultad de Ciencias, Universidad de Chile, Santiago, Chile;Departament de Bioquı́mica y Biologı́a Molecular, Facultat de Quı́mica, Universitat de Barcelona, Barcelona, Spain

关键词: Metabolic control analysis;    Control coefficient;    Hexokinase;    Glucose-6-phosphate dehydrogenase;    Glycogen synthesis;    Pentose phosphate pathway;    Frog oocyte;   

DOI  :  10.1016/S0014-5793(00)01646-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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 ¹⁴CO₂ (the oxidative portion of the pentose phosphate pathway) was investigated by microinjection of [1-¹⁴C]glucose and measurements of the radioactivity in glycogen and CO₂. 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 ¹⁴CO₂ 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.

【 授权许可】

Unknown