6Phosphogluconolactone

6-Phosphogluconolactone is a δ-lactone intermediate in the oxidative branch of the pentose phosphate pathway (PPP). It is formed when glucose-6-phosphate is oxidized by glucose-6-phosphate dehydrogenase, with NADP+ as the electron acceptor, producing NADPH.

The lactone is rapidly hydrolyzed by 6-phosphogluconolactonase to 6-phosphogluconate, which then undergoes oxidative decarboxylation by 6-phosphogluconate dehydrogenase to ribulose-5-phosphate, yielding another molecule of NADPH and releasing CO2.

In aqueous solution 6-phosphogluconolactone is relatively unstable and tends to convert to 6-phosphogluconate; enzymes accelerate this interconversion.

The oxidative phase of the PPP thereby links glucose metabolism to nucleotide biosynthesis and cellular redox balance by supplying NADPH and ribose-5-phosphate.

6-Phosphogluconolactone is found across bacteria, archaea, and eukaryotes, reflecting the conserved nature of the PPP; its enzymatic steps are subject to regulation in response to cellular needs.