Solubilization, Purification and Properties of Hexose 6-Phosphate Dehydrogenase from Guinea Pig Liver Microsomes

The solubilization, purification and property of hexose 6-phosphate dehydrogenase from guinea pig liver microsomes is described. The enzyme was effectively solubilized by ammonium hydroxide in the presence of 0.5% detergent, and highly purified. The enzyme showed a different pH dependency for various substrates. The optimum pH for galactose 6-phosphate, glucose 6-phosphate and glucose was 8.5,10.2 and more alkaline, respectively. Km values for the substrates were also changed, pH dependently. The enzyme exhibited the lowest Km values in an order of 10^<-6>M for glucose 6-phosphate at pH 7.0. The enzyme activity was inhibited by CaCl_2 and HgCl_2,but other metal compounds, steroids, pCMB and NADPH did not inhibit the activity. The antibody against the purified enzyme inhibited the enzyme activity of Triton X-100 treated microsomes while the inhibition of the enzyme activity of intact microsomes by antibody was very low.