Glucose-6-phosphate dehydrogenase (G6PD) catalyzes the conversion of glucose-6-phosphate to 6-phosphoglucono-δ-lactone, the first and rate-limiting step in the pentose phosphate pathway. It is critical metabolic pathway that supplies reducing energy to cells (such as erythrocytes) by maintaining the level of co-enzyme nicotinamide adenine dinucleotide phosphate (NADPH), and for the production of pentose sugars. The production of NADPH is of great importance for tissues actively engaged in biosynthesis of fatty acids and/or isoprenoids, such as the liver, mammary glands, adipose tissue, and the adrenal glands. The NADPH also maintains the level of glutathione in these cells that helps protect the red blood cells against oxidative damage. Deficiencies in G6PDH predispose individuals to non-immune hemolytic anemia. AAT Bioquest’s Amplite Colorimetric Glucose-6-Phosphate Dehydrogenase Assay Kit provides a simple, sensitive and rapid fluorescence-based method for detecting G6PD in biological samples such as serum, plasma, urine, as well as in cell culture samples. In the enzyme coupled assay, G6PD activity is proportionally related to the concentration of NADPH that is specifically monitored by a chromogenic NADPH sensor. The absorption signal can be read  by an absorption microplate reader at ~575 nm. With the G6PD assay kit, we were able to detect as little as 3 mU/ml G6PD in a 100 L reaction volume.