Succinate thiokinase, reaction catalyzed

Succinyl-CoA synthetase (SCS), also known as succinate thiokinase (STK) or succinate CoA ligase ( 6.2.1.4-5), is so far the only known hydrogenosomal enzyme directly involved in energy conservation. The protein catalyzes the reversible, substrate-level phosphorylation of ADP or GDP to the respective triphosphate at the expense of the high-energy thioester bond of succinyl-CoA. Succinate and CoA are released in the reaction. The I vaginalis enzyme... 

In this complex reaction catalyzed by succinyl-CoA synthase (succinate thiokinase), the energy-rich thioester linkage of succinyl-CoA is hydrolyzed with release of free energy that is conserved in the substrate phosphorylation of GDP with phosphate to form GTP ... 

Succinyl-CoA synthetase (also called succinate thiokinase) is an enzyme of the citric acid cycle that catalyzes the reaction below ... 

The cleavage of the thioester bond of succinyl CoA is coupled to the phosphorylation of a purine nucleoside diphosphate, usually GDP. This reaction is catalyzed by succinyl CoA synthetase (succinate thiokinase). This enzyme is an a2 2 heterodimer the functional unit is one a(3 pair. The mechanism is a clear example of energy transformations energy inherent in... 

The metabolic pathways involved in the synthesis of P(3HB-co-4HB) from 4-hydroxybutyric acid are shown in Fig. 2.4. Transferase or thiokinase catalyzes the conversion of 4-hydroxybutyric acid into 4HB-CoA, which is then used as the substrate by the PHA synthase in the polymerization reaction. The catabolism of 4-hydroxybutyric acid also leads to the formation of intermediates such as 3-hydroxybutyryl-CoA, resulting in the accumulation of P(3HB-co-4HB) copolymer. The main catabolic pathway for 4HB is probably via succinic acid semialdehyde and succinic acid pathways, which are catalyzed by 4HB dehydrogenase and succinic acid semialdehyde dehydrogenase (Valentin et al. 1995 Lutke-Eversloh and Steinbiichel 1999). All precursor substrates for the generation of 4HB monomers are first converted into 4HB-CoA, which is the immediate substrate for PHA synthase. 

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