In the G6PD-based method, what spectrophotometric detection is used?

In the G6PD-based method, what spectrophotometric detection is used?

• A. NADPH increased absorbance at 340 nm
• B. NADH at 340 nm
• C. FADH2 at 450 nm
• D. NAD(P)H at 520 nm

Answer: (A)

NADPH formation is detected by measuring absorbance at 340 nm because the reduced cofactor NADPH absorbs strongly at that wavelength. In the glucose-6-phosphate dehydrogenase reaction, NADP+ is reduced to NADPH, so the rate of NADPH production is directly reflected by an increasing absorbance at 340 nm. The other options point to detecting different cofactors or at wavelengths not used for this assay: FADH2 would be read around 450 nm, and NAD(P)H detection at 520 nm isn’t standard for this reaction. Thus, the assay monitors NADPH increase at 340 nm.

NADPH formation is detected by measuring absorbance at 340 nm because the reduced cofactor NADPH absorbs strongly at that wavelength. In the glucose-6-phosphate dehydrogenase reaction, NADP+ is reduced to NADPH, so the rate of NADPH production is directly reflected by an increasing absorbance at 340 nm. The other options point to detecting different cofactors or at wavelengths not used for this assay: FADH2 would be read around 450 nm, and NAD(P)H detection at 520 nm isn’t standard for this reaction. Thus, the assay monitors NADPH increase at 340 nm.