Hexose monophosphate shunt. See

A total of 14 NADPH molecules are utilized to make each palmitate molecule. It comes from three sources the malic enzyme (see earlier) provides one NADPH molecule for every acetyl-CoA molecule generated from citrate. For palmitate, this accounts for eight NADPH molecules. The rest must be derived largely from the hexose monophosphate shunt (see Chapter 18). A minor source of NADPH is cytosolic isocitrate dehydrogenase (see Chapter 18). The synthesis of one palmitate molecule thus requires an equivalent of 7 + (3)14 = 49 ATP molecules. 

The oxidative pathway for the metabolism of D-glucose 6-phosphate (XLV), distinctive from the glycolytic, Embden-Meyerhof route (see p. 200) and known as the hexose monophosphate shunt, was suggested by certain experiments of Warburg,200 Gerischer,207 Lipmann,208 and Dickens209... 

Approximately 5 to 10% of the glucose metabolized by red blood cells is used to generate NADPH by way of the hexose monophosphate shunt. The NADPH is used to maintain glutathione in the reduced state. The glutathione cycle is the red blood cell s chief defense against damage to proteins and lipids by reactive oxygen species (see Chapter 24). 

---