JBC, Vol. 254, Issue 19, 9441-9447, Oct, 1979
Purification of a new high activity form of glucose-6-phosphate dehydrogenase from rat liver and the effect of enzyme inactivation on its immunochemical reactivity
M. L. Dao, J. J. Watson, R. Delaney and B. C. Johnson
A new form of cytoplasmic glucose-6-phosphate dehydrogenase (E.C.1.1.1.49)
was purified from rat liver by protamine sulfate precipitation, ammonium
sulfate fractionation, ion exchange chromatography with diethylaminoethyl
cellulose, and affinity chromatography with Cibacron blue agarose and NADP
agarose. This form of the enzyme has a specific activity of over 600
units/mg of protein and gives essentially a single band by polyacrylamide
gel electrophoresis. The form of the enzyme isolated by this purification
method is 3 times more active than the form purified from liver by
previously reported procedures. The relative mass of this pure
glucose-6-phosphate dehydrogenase enzyme was determined by disc gel
electrophoresis to be 269,000. This high activity glucose-6-phosphate
dehydrogenase enzyme, after inactivation by reaction with palmityl-CoA, was
no longer precipitated by specific rabbit and goat antisera to this
purified enzyme. Thus, the possibility still exists that starved fat-refed
animals contain glucose-6-phosphate dehydrogenase (G6PD) enzyme protein in
an inactivated form no longer detectable by either enzyme activity or
immunoprecipitation.