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Hexokinase bound to rat brain mitochondria uses externally added ATP more efficiently than internally generated ATP

Authors
Journal
Biochimica et Biophysica Acta (BBA) - Bioenergetics
0005-2728
Publisher
Elsevier
Publication Date
Volume
1057
Issue
1
Identifiers
DOI: 10.1016/s0005-2728(05)80095-7
Keywords
  • Mitochondrion
  • Hexokinase
  • Brain
  • Tumor
  • Atp

Abstract

The rates of glucose phosphorylation by bound hexokinase were investigated in mitochondria isolated from rat brain. Initial rates obtained either with ATP generated from oxidative phosphorylation or with ATP added externally were compared. Our results show that the external ATP supports a 2–3-fold higher hexokinase activity than does ATP generated by oxidative phosphorylation under State 3 conditions. ATP formed by mitochondrial creatine kinase in the presence of creatine phosphate also supports higher initial rates of glucose phosphorylation than does oxidative phosphorylation. The data suggest that concentrations of ATP present in the cytosol of normal tissue will probably maintain higher rates of glucose phosphorylation than ATP being exported directly from the mitochondrial matrix at maximal State 3 rates.

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