Yeast glucose-6-phosphate dehydrogenase

In our assay for TPNH-cytochrome c reductase, we used glucose 6-phosphate and Zwischenferment (yeast glucose 6-phosphate dehydrogenase) to generate reduced TPN, and thus began my interest in the oxidative pathway. This also introduced me to the powerful tool of absorption spectrophotometry, 3 years before the Beckman spectrophotometer. Warburg, who was probably the first to build an instrument for enzyme studies, had discovered the absorption bands of the reduced coenzymes, but he was devoted to his manometric techniques, and it remained for Haas and myself to apply the new technique to the routine assay of an enzyme-catalyzed reaction, which we measured by following the rate of appearance of the reduced band of cytochrome c. 

On the other hand, a number of native proteins tested were found to be better substrates for cathepsin M than for cathepsin B (Table IV). Muscle and liver aldolases were inactivated by cathepsins M and B at comparable rates (Table IV) but yeast glucose-6-phosphate dehydrogenase was inactivated much more rapidly by cathepsin M and neither rabbit liver pyruvate kinase nor rabbit muscle glyceraldehyde-3-phosphate dehydrogenase was inactivated on incubation with cathepsin B. 

N4. Noltmann, E. A., Gubler, C. J., and Kuby, S. A., Glucose-6-phosphate dehydrogenase (Zwischenferment). I. Isolation of the crystalline enzyme from yeast. J. Biol. Chem. 236, 1225-1230 (1961). 

Glucose-6-phosphate dehydrogenase (from Torula yeast) suspension Activity 520 Units/mg protein, Sigma (Lot 13H80602), USA... 

Hexokinase 280 kU/l/glucose-6-phosphate dehydrogenase 140 kU/1 hexokinase and glucose-6-phosphate dehydrogenase from yeast, suspended in 3.2 M ammonium sulfate solution. Dilute stock solutions with 3.2 M ammonium sulfate solution according to specified activity to 280 kU/1 and 140 kU/1, respectively. 

Chen E, Cheng A, Lee A, et al. Sequence of human glucose-6-phosphate dehydrogenase cloned in plasmids and a yeast artificial chromosome. Genomics 10 792-800,1991. 

McCreath, G. E., Chase, H. A., and Lowe, C. R. (1992). Novel affinity separations based on perfluorocarbon emulsion—use of perfluorocarbon affinity emulsions for the direct extraction of glucose-6-phosphate dehydrogenase from homogenized Baker s yeast.. Chromatogr. 659, 275-287. 

Glucose-6-phosphate dehydrogenase solution (10 units/ ml)—We purchase this enzyme from Sigma (catalog G-6378), which is derived from baker s yeast. Reconstitute the enzyme in distilled water as per the manufacturer s instructions. Consult the specification sheet (lot-specific, usually 200-400 units/mg of protein) to determine a dilution of the enzyme stock that will yield a 10-unit/ml solution (dilution is performed in distilled water). Store the remainder of the reconstituted stock enzyme solution in small aliquots at —20°C for use in future semesters. 

Glucose-6-phosphate Dehydrogenase Origin baker s yeast... 

For the preparation of 6-phosphogluconate from glucose-6-phosphate with commercially available glucose-6-phosphate dehydrogenase from yeast the results are summarised in Table 25. Electrochemical experiments using the anode as the electron acceptor are shown in Section 6. 

The formation of trehalose 6 -phosphate by the yeast enzyme appears to be irreversible. This must be attributed to some factor other than an unfavorable equilibrium, since reversibility of the reaction could not be demonstrated even when n-glucose 6-phosphate dehydrogenase or uridine 5-(a-D-glucopyranosyl pyrophosphate) dehydrogenase were added in an attempt to drive the reaction in the opposite direction. An upper limit of 4400 cal. was calculated for the —AF° of hydrolysis of the glucosidic bond of a,a-trehalose 6 -phosphate this value is admittedly unreliable. 

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