Acetate:succinate CoA-transferase

Succinyl-CoA acetate CoA transferase (acetate/succinate CoA transferase (ASCT), 2.8.3.8) catalyzes the transfer of the CoA moiety between acetate and succinate and produces the hydrogenosomal end product, acetate. This activity was first detected in the hydrogenosomes of T. foetus in the mid-1970s (Lindmark 1976) and subsequently in T. vaginalis as well (Steinbiichel and Muller 1986). However, the enzyme has not been purified or characterized in any detail, nor has it been sequenced. During the preliminary analysis of the... 

Fig. 1 Enzymes localized to B. hominis mitochondrial-like organelle. The enzymes are 1 malic enzyme, 2 pyruvate NADP oxidoreductase, 3 acetate succinate CoA transferase, 4 succinate thiokinase, 5 a-ketoglutarate dehydrogenase, 6 isocitrate dehydrogenase, and 7 aconitase...

In the oxidative branch of malate dismutation, malic enzyme oxidizes malate to pyruvate, which is then further oxidized to acetyl-CoA by pyruvate dehydrogenase, an enzyme complex specially adapted to anaerobic functioning in Ascaris suum and possibly in other parasitic helminths like the trematode F. hepatica and the cestode Dipylidium caninum (Diaz and Komuniecki, 1994 Klingbeil et al., 1996). Parasitic helminths like F. hepatica use an acetate succinate CoA-transferase (ASCT) for... 

Van Hellemond, J.J., Opperdoes, F.R. and Helens, A.G.M. (1998) Trypanosomatidae produce acetate via a mitochondrial acetate succinate CoA-transferase. Proceedings of the National Academy of Sciences USA 95, 3036-3041. 

Fig. 5.2. Possible metabolic pathways in facultative anaerobic mitochondria. Shaded boxes show components of the electron-transport chain used during hypoxia, open boxes are components used during aerobiosis, and the hatched boxes (complex I and ATP-synthase) are components used under aerobic as well as anaerobic conditions. ASCT acetate succinate CoA-transferase, C cytochrome c, Cl, CIII and CIV complexes I, III and IV of the respiratory chain, CITR citrate, ECR enoyl-CoA reductase (such as present in Ascaris suum), ETF electron-transfer flavoprotein, ETF RQ OR electron-transfer flavoproteimrhodoquinone oxidoreductase, FRD fumarate reductase, FUM fumarate, MAE malate, OXAC oxaloacetate, PYR pyruvate, RQ rhodoquinone, SDH succinate dehydrogenase, SUCC succinate, Succ-CoA succinyl-CoA, TER trans-2-enoyl-CoA reductase (such as present in E. gracilis), UQ ubiquinone...

Fig. 1.2. Maps of pyruvate metabolism in trichomonad hydrogenosomes published in 1976 (a) and 2003 (b). Metabolism of malate omitted. 1 pyruvate ferredoxin oxidoreductase, 2 hydroge-nase, 3 electron transport protein (unidentified in 1976, known to be ferredoxin in 2003), 4 acetate succinate coenzyme A (CoA) transferase, 5 succinyl-CoA synthase, 6 acetyl-CoA synthase (its presence was not confirmed later), (a From Fig. 2 in Muller 1976 b from Fig. 7.3 in Muller 2003)...

Coenzyme A Transferases. In addition to enzymes that incorporate CoA into acyl thioesters, a group of enzymes have been found to form the CoA derivatives of certain acids by transfer of CoA from a preexisting thioester. The first example of this type of reaction to be found was the CoA transphorase of C. Muyveri. This enzyme transfers CoA among various small fatty acids. Bacterial enzymes have been implicated in CoA transfers between propionate and succinate, acetate and formate, ... 

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