In the hexokinase-based glucose assay, which cofactor is reduced to NADPH?

In the hexokinase-based glucose assay, which cofactor is reduced to NADPH?

• A. NADP+
• B. NAD+
• C. FAD
• D. FMN

Answer: (A)

In this assay, after glucose is phosphorylated by hexokinase, the next step is carried out by glucose-6-phosphate dehydrogenase, which uses NADP+ as the electron acceptor. NADP+ accepts electrons and is reduced to NADPH. The amount of NADPH produced is proportional to the glucose concentration, and NADPH is measured because it has a distinct absorbance at 340 nm, allowing quantification. NAD+ would be reduced to NADH in other metabolic reactions, and FAD or FMN are flavin cofactors used by different dehydrogenases; they do not participate in this particular glucose assay.

In this assay, after glucose is phosphorylated by hexokinase, the next step is carried out by glucose-6-phosphate dehydrogenase, which uses NADP+ as the electron acceptor. NADP+ accepts electrons and is reduced to NADPH. The amount of NADPH produced is proportional to the glucose concentration, and NADPH is measured because it has a distinct absorbance at 340 nm, allowing quantification.

NAD+ would be reduced to NADH in other metabolic reactions, and FAD or FMN are flavin cofactors used by different dehydrogenases; they do not participate in this particular glucose assay.