A-glycerophosphate dehydrogenase

Ovalbumin Conalbumin Ovomucoid Lysozyme Vitellogenin apo-VLDL Glucose-6-P-dehydrogenase Oviduct Oviduct (liver) Oviduct Oviduct Liver Liver Uterus Thyroid Hormones Carbamyl phosphate synthase Growth hormone Prolactin ( ) a-Glycerophosphate dehydrogenase Malic enzyme Liver Pituitary Pituitary Liver (mitochondria) Liver... 

The oxidation of L-glycerol 3-phosphate to dihydroxyacetone phosphate is catalyzed by two different enzymes. One is the cytoplasmic NAD-linked a-glycerophosphate dehydrogenase, and the other is the mitochondrial enzyme, which appears to contain flavin and iron. The latter enzyme was first studied by Green in 1936 (223). It was shown to be associated with respiratory particles, and widely distributed in animal tissues. The highest concentration of the enzyme was found in the brain. Lardy and co-workers (234) studied the enzyme in deoxycholate-solubilized particles obtained from skeletal muscle, confirmed the finding... 

Mitochondria from the flight muscle of house flies, Mtisca domestica, have been shown to oxidize a-glycerophosphate at exceptionally high rates (233, 234). This activity was shown to be inhibited by EDTA. It is believed that in these and other mitochondria the combined action of the soluble and the particle-bound a-glycerophosphate dehydrogenases... 

Flavin-containing a-glycerophosphate dehydrogenases have been found also in Streptococcus faecalis ( 44) and Propionibacterium arabinosum (24B). The enzyme from 5. faecalis is reported to contain FAD, have a Km for < -glycerophosphate of 4 mM, and a pH optimum of 5.8. In addition to dyes, this enzyme can interact directly with molecular oxygen to form H2O2. The preparation from P. arabinosum is particle-bound, has a Km for a-glycerophosphate of 26 /lAf, and is claimed to contain flavin and nonheme iron. 

Dichlorophenolindophenol choline dehydrogenase and, 261 cytochrome 6j and, 267 cytochrome P-450 reductase and, 167 a-glycerophosphate dehydrogenase and,... 

Fig. 3.1. A, The respiratory chain. Q and c stand for ubiquinone and cytochrome c, respectively. Auxiliary enzymes that reduce ubiquinone include succinate dehydrogenase (Complex II), a-glycerophosphate dehydrogenase and the electron-transferring flavoprotein (ETF) of fatty acid oxidation. Auxiliary enzymes that reduce cytochrome c include sulphite oxidase. B, Thermodynamic view of the respiratory chain in the resting state (State 4). Approximate values are calculated according to the Nernst equation using oxidoreduction states from work by Muraoka and Slater, (NAD, Q, cytochromes c c, and a oxidation of succinate [6]), and Wilson and Erecinska (b-562 and b-566 [7]). The NAD, Q, cytochrome b-562 and oxygen/water couples are assumed to equilibrate protonically with the M phase at pH 8 [7,8]. E j (A ,/ApH) for NAD, Q, 6-562, and oxygen/water are taken as —320 mV ( — 30 mV/pH), 66 mV (- 60 mV/pH), 40 mV (- 60 mV/pH), and 800 mV (- 60 mV/pH) [7-10]. FMN and the FeS centres of Complex I (except N-2) are assumed to be in redox equilibrium with the NAD/NADH couple, FeS(N-2) with ubiquinone [11], and cytochrome c, and the Rieske FeS centre with cytochrome c [10]. The position of cytochrome a in the figure stems from its redox state [6] and its apparent effective E -, 285 mV in...

Fig. 36. Absorption spectrum of partially purified a-glycerophosphate dehydrogenase, protein concentration 13 mg/ml. (O) Spectrum of oxidized enzyme. The difference spectra (shown in the insert) were recorded after the addition of a few granules of sodium hydrosulfite ( ) or 5 Mmoles substrate (O) iu a total volume of 0.2 ml. In the difference spectra, a decrease in optical density indicates bleaching. From Ringler (225).

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