Pentose phosphate pathway

The pentose phosphate pathway oxidizes glucose to make NADPH and other carbohydrates for biosynthesis (see Figure 1  ). The major route for reduction of NADP to NADPH is the reaction of glucose‐6‐phosphate through two successive reactions. In the first, carbon 1 of glucose is oxidized from an aldol to an esterform (actually, an internal ester, called a lactone) by glucose‐6‐phosphate dehydrogenase. In the second reaction, the same carbon is further oxidized to CO ₂and released, leaving behind a 5‐carbon sugar, in a reaction catalyzed by 6‐phosphogluconolactone‐dehydrogenase. Both reactions reduce NADP to NADPH. The 5‐carbon residue is ribulose‐5‐phosphate.


source : http://www.cliffsnotes.com/sciences/biology/biochemistry-i/carbohydrate-metabolism-ii/the-pentose-phosphate-pathway
http://en.wikipedia.org/wiki/Pentose_phosphate_pathway