Table 2. Evaluation of various enzymatic assays for glucose dehydrogenase activity of GDH1E5.

Co-factor	external electron acceptor	Enzyme activity [U/mg]a
NAD+	–	no activity
NADP+	–	no activity
–	p-nitrosoaniline(BM53.0861)	91.5 (±0.4)
–	DCPIP	48.0 (±0.9)

^a All data represent the average of triplicate determinations ± standard derivation.

All enzyme assays were carried out using purified GDH1E5 over 5 min at 35°C and 75 mM glucose as a substrate. NAD(P)⁺ was used in concentrations of 5 mM respectively. The formation of reduced NAD(P)H was followed by an increase in absorbance at 340 nm. The enzymatic reduction of p-nitrosoaniline BM53.0861 and DCPIP was followed by an increase in absorbance at 620 nm for the nitrosoaniline and a decrease in absorbance at 600 nm for the dichloroindophenol.