Yeast Glutathion

The three enzymes are quite specific for their respective pyridine nucleotide substrates. Under conditions normally used for assay, lipoamide dehydrogenase is less than % as active with NADPH as with NADH IS) and thioredoxin reductase is less than 1% as active with NADH as with NADPH 36, Sff). Lipoamide dehydrogenase can transfer electrons to a number of NAD analogs 37). Yeast glutathione reductase is quite specific for NADPH 60), but the erythrocyte enzyme is 20% as active with NADH as with NADPH under the conditions of the standard assay 30,40,61). 

Fia. 1. Yeast glutathione reductase. Spectra of the oxidized and 2-electron-reduced... 

The reactions in Eq. (10), proceeding to the right from E, are part of normal catalysis as shown in Fig. 10 (SI, S3). The association of E with NADP leads to a dead end complex. In the reaction of yeast glutathione reductase with NADPH, EH,-NADPH appears to be formed in the dead time of the rapid reaction spectrophotometer (co. 3 msec) when observation is at 540 nm (344), however, if 3.4 /iM EH,(free) is mixed with 20 fiM NADPH, Eq. (11), a minimum rate of complex formation of... 

Fio. 13. Yeast glutathione reductase, semiquinone anion production from the 2-electron reduced form. Curve 1, oxidized enzyme, anaerobic conditions, pH 7.6 curve 2, 1 min after the addition of 1 equivalent of NADPH curve 3, 22 hr later curve 4, 1 hr after the addition of 10 equivalents of NADP curve 5, 235 hr later curve 6, 185 hr after the addition of 5 equivalents of NADPH and ciirve 7, 36 min after opening to air. 

Styblo, M., Serves, S.V., Cullen, W.R., Thomas, D.J. (1997). Comparative inhibition of yeast glutathione reductase by arsenicals and arsenothiols. Chem. Res. Toxicol. 10 27-33. 

Flavoproteins Yeast fatty acyl-CoA oxidase Porcine liver fatty acyl-CoA dehydrogenase Yeast glutathione reductase Egg-white flavoprotein Old yellow enzyme D-amino acid oxidase NADPH-cytochrome P-450 reductase Flavin Type of bonding between flavin and protein. Chemistry of charge-transfer complexes involving flavin and second ligand (e.g. phenolor amino-acid derivative )... 

Experiments have been reported elsewhere in which chlorophyll, as well as other alcohol-soluble material, was removed from chloroplast fragments, and a light-dependent reduction of oxidized glutathione, via the TPN-linked yeast glutathione reductase, was observed upon recombination of the chlorophyll extract with the colorless fraction (374a). 

Snoke, j. E. Isolation and properties of yeast glutathione synthetase. J. Biol. Chem. 213, 813 (1955). 

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