PubMed · 12981017
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H J STRECKER, S KORKES. 1952. Glucose dehydrogenase.. https://pubmed.ncbi.nlm.nih.gov/12981017/
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The coupled activation of two enzymes: glucose dehydrogenase (GDH) and horseradish peroxidase (HRP), is used to construct the parallel-operating AND and InhibAND logic gates. The added substrates for the respective enzymes, glucose and H(2)O(2), act as the gate inputs, while the biocatalytically generated NADH and gluconic acid provide the output signals that follow the operations of the gates. The two gates are generated in the same vial, thus allowing the logic operations to take place in parallel, and the simultaneous readout of the functions of the gates.
The kinetic mechanism of glucose dehydrogenase (EC 1.1.1.47) from Halobacterium salinarum was studied by initial velocity and product inhibition methods. The results suggest that both, in the forward and reverse direction, the reaction mechanism is of Bi Bi sequential ordered type involving formation of ternary complexes. NADP+ adds first and NADPH formed dissociates from the enzyme last. For the reverse direction, NADPH adds first and NADP+ leaves last. Product inhibition experiments indicate that (a), the coenzymes compete for the same site and form of the enzyme and (b), ternary abortive complexes of enzyme-NADP(+)-glucono-delta-lactone and enzyme-NADPH-glucose are formed. All the other inhibitions are noncompetitive.
A method is described for xylose determination on the Ciba-Corning 550 Express that utilizes the slower enzymatic action of glucose dehydrogenase (GDH) on D-xylose, after prior removal of glucose. Glucose oxidase is added to serum or urine and incubated for 120 min at 37 degrees C. After incubation, a perchloric acid filtrate of the specimen is added to the GDH reagent in the presence of NAD, the amount of NADH produced being proportional to the amount of xylose present. Absorbances at 340/380 nm are read at 180 s and 600 s after the reagent is added. The standard curve is linear to 7.50 mmol/L and the method showed day-to-day imprecision (CV%) of 2.7 (n = 18), 1.8 (n = 17), and 2.2 (n = 17) at concentrations of 0.62, 1.18, and 2.60 mmol/L, respectively. Recoveries ranged from 99 to 106% for sera and 96 to 100% for urines. Good correlation was obtained when tested against established automated ferricyanide and p-bromoaniline methods.