d-Glucose-6-phosphate and d-Fructose-6-phosphate: Determination with Glucose-6-Phosphate Dehydrogenase and Phosphoglucose Isomerase

摘要: Publisher Summary This chapter elaborates the enzymatic determination of D -glucose-6-phosphate and -fructose-6-phosphate with glucose-6-phosphate dehydrogenase phosphoglucose isomerase. The method is based on principle that (G6P-DH, Zwischenferment) catalyzes oxidation (G-6-P) by triphosphopyridine nucleotide (TPN). With a suitable excess TPN (about five times G-6-P concentration) virtually quantitative. reaction measured increase in optical density at 340 or 334 (also 366) mμ when reduced. For purity enzyme preparations, G6P-DH preparation should have specific activity about 4000 units/mg (according to Biicher) 70 Racker). Contamination hexokinase not exceed 0.2%, 6-phosphogluconic 0.01%, isomerase 0.05%, glutathione reductase 0.5% (relative preparation). Also, must be practically free from flavin enzymes. Phosphoglucose ca . 10 4 Biicher). It dehydrogenase, phosphoglucomutase, reductase, enzymes (TPNH oxidase).