Biochemical studies of galactokinase from neurospora crassa

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Jun-Lan Wang (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
William Bates

Abstract: Galactokinase (ATP: D-galactose 1-phosphotransferase, EC No. was demonstrated in extracts prepared from the fungus Neurospora crassa. This enzyme was found to have maximal activity at pH 8.5 in Tris-HCl buffer, and optimal concentrations of magnesium chloride and adenosine triphosphate were determined. An important part of the study was comparison of the galactokinase enzyme with the closely related enzyme glucokinase (ATP: Dglucose 6- phosphotransferase, EC No. from Neurospora. Glucokinase was found to be much more thermostabile than galactokinase, and both enzyme activities sedimented at the rate of approximately 4 S on glycerol or sucrose gradients in the preparative ultracentrifuge, Electrophoretic analysis of extracts containing both enzyme activities clearly demonstrated the migration pattern of glucokinase, but galactokinase was inactivated during this separation procedure. This electrophoretic study therefore provided no evidence concerning the separate identity of the proteins associated with the two activities. The process of extraction of protein from the mycelium, however, demonstrated that glucokinase is freely extractable, but a large portion of the total galactokinase activity is associated with some insoluble component of the cell debris. This suggests that separate proteins provide the two enzyme activities, but the evidence on this point is not definitive because of the possibility of activation, inhibition, or steric effects associated with attachment to a cellular organelle.

Additional Information

Language: English
Date: 1970
Neurospora crassa

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