Effects of Dehydroepiandrosterone and its Conjugates upon the Activity of Glucose-6-Phosphate Dehydrogenase

Abstract

The inhibition of human placental glucose-6-phosphate dehydrogenase by dehydroepiandrosterone, dehydroepiandrosterone sulfate and dehydroepiandrosterone sulfatide was investigated, using a 120-fold purified enzyme preparation. At a 10^-6 M concentration the synthetic steroid sulfatide still caused a 29 % inhibition as compared to an 18 % inhibition by the free steroid. The inhibition of the enzyme was found to be of the non-competitive type with regard to both substrates: glucose-6-phosphate and NADP. Since under physiological conditions, however, free dehydroepiandrosterone seems to prevail in human placenta, any regulation of said enzyme activity may be mediated rather through the free steroid than through its sulfatide.