intermediates of fatty acid biosynthesis). Inhibition due to NADPH depends upon the cytosolic NADP+/NADPH ratio, which in the liver is about 0.015 (compared to about 725 for the NAD+/NADH ratio in the cytosol).
The gluconolactone produced in step 1 is hydrolytically unstable and readily undergoes a spontaneous ring-opening hydrolysis, although an enzyme, glu-conolactonase, accelerates this reaction (Figure 23.28). The linear product, the sugar acid 6-phospho-D-gluconate, is further oxidized in step 3.
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