Studies on the Regulation of Rat Liver Pyruvate Kinase and Fructose-1,6-Bisphosphatase

Cytoplasmic thioltransferase purified from rat liver [Axelsson, Eriksson & Mannervik (1978) Biochemistry 17, 2978–2984] catalyses the formation and decomposition of mixed disulphides of proteins and glutathione. The enzyme was found to catalyse the reversible thiol-disulphide interchange between glutathione disulphide and a crude thiol-containing protein fraction from rat liver. This finding indicates a role of the thioltransferase in the regulation of the ‘glutathione status’ of the cell. Specifically, it was found that thioltransferase catalyses the reactivation of pyruvate kinase from rat liver that had previously been inactivated by glutathione disulphide. It is suggested that thioltransferase may have a general role in regulatory processes involving thiol-disulphide interchange.

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Expression of rat liver fructose-1,6-bisphosphatase in Escherichia coli

Biochemical and Biophysical Research Communications ◽

10.1016/0006-291x(91)90900-r ◽

1991 ◽

Vol 176 (1) ◽

pp. 137-144 ◽

Cited By ~ 9

Author(s):

M.Raafat El-Maghrabi ◽

Simon J. Pilkis

Keyword(s):

Escherichia Coli ◽

Rat Liver ◽

Fructose 1,6 Bisphosphatase

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Regulation of phosphoenolpyruvate carboxykinase and pyruvate kinase in Saccharomyces cerevisiae grown in the presence of glycolytic and gluconeogenic carbon sources and the role of mitochondrial function on gluconeogenesis

Canadian Journal of Microbiology ◽

10.1139/m86-180 ◽

1986 ◽

Vol 32 (12) ◽

pp. 969-972 ◽

Cited By ~ 7

Author(s):

Albert J. Wilson ◽

J. K. Bhattacharjee

Keyword(s):

Saccharomyces Cerevisiae ◽

Pyruvate Kinase ◽

Growth Medium ◽

Phosphoenolpyruvate Carboxykinase ◽

Carbon Sources ◽

Absolute Requirement ◽

Fructose 1,6 Bisphosphatase ◽

Futile Cycling ◽

Respiratory Deficient

Phosphoenolpyruvate carboxykinase (PEPCKase) and pyruvate kinase (PKase) were measured in Saccharomyces cerevisiae grown in the presence of glycolytic and gluconeogenic carbon sources. The PEPCKase activity was highest in ethanol-grown cells. However, high PEPCKase activity was also observed in cells grown in 1% glucose, especially as compared with the activity of sucrose-, maltose-, or galactose-grown cells. Activity was first detected after 12 h when glucose was exhausted from the growth medium. The PKase activity was very high in glucose-grown cells; considerable activity was also present in ethanol- and pyruvate-grown cells. The absolute requirement of respiration for gluconeogenesis was demonstrated by the absence or significantly low levels of PEPCKase and fructose-1,6-bisphosphatase activities observed in respiratory deficient mutants, as well as in wild-type S. cerevisiae cells grown in the presence of glucose and antimycin A or chloramphenicol. Obligate glycolytic and gluconeogenic enzymes were present sumultaneously only in stationary phase cells, but not in exponential phase cells; hence futile cycling could not occur in log phase cells regardless of the presence of carbon source in the growth medium.

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