Is thermostability of glucose-6-phosphatase indeed dependent on a stabilizing protein?
Partial purification of glucose-6-phosphatase from rat liver microsomes by solubilization of the membranes with the non-ionic detergent Triton X-114 at pH 6.5 and the removal of inactivating detergent by hydrophobic chromatography results in a thermostable enzyme protein which is not dependent on stabilizing phospholipids or proteins. The readdition of low amounts of detergent immediately causes a conversion into a thermo-unstable phosphohydrolase protein. Thus these findings present evidence that heat instability of partially purified glucose-6-phosphatase derives from traces of inactivating detergent changing the structural properties of the phosphohydrolase rather than from the absence of the postulated specific stabilizing protein.
D000818:Animals; D003902:Detergents; D005952:Glucose-6-Phosphatase / Q000302:isolation & purification*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008297:Male; D008565:Membrane Proteins; D008862:Microsomes, Liver / Q000201:enzymology; D017830:Octoxynol; D011092:Polyethylene Glycols; D051381:Rats; D011919:Rats, Inbred Strains; D012995:Solubility
D003902:Detergents; D008565:Membrane Proteins; D011092:Polyethylene Glycols; D017830:Octoxynol; C010615:Nonidet P-40; D005952:Glucose-6-Phosphatase