Succinyl coenzyme A synthetase

Lahti CJ, d Oliveira CE, Johnson PJ (1992) 3-Succinyl-coenzyme-A synthetase from Trichomonas vaginalis is a soluble hydrogenosomal protein with an amino-terminal sequence that resembles mitochondrial presequences. J Bacteriol 174 6822-6830... 

Wedding, R.T., Norman, A.W., and Black, M.K., Detection of phosphohistidine in succinyl coenzyme A synthetase isolated from Jerusalem artichoke mitochondria, Plant Cell Physiol., 7, 707-710, 1966. 

Mechanism Succinyl Coenzyme A Synthetase Transforms Types of Biochemical Energy... 

S.M. Mayer, S.I. Beale (1992). Succinyl-Coenzyme A Synthetase and its role in 5-aminolevulinic acid biosynthesis in euglena gracilis. Plant Physiol., 99, 482-487. 

Two turns of the TCA cycle, with NADH produced at the pyruvate dehydrogenase, isocitrate dehydrogenase, alpha-ketoglutarate, and malate dehydrogenase steps and FADH2 produced at the succinate dehydrogenase step and GTP (equivalent to ATP) produced at the succinyl-coenzyme A synthetase step. 

Contribution of Subunit Interactions to the Effectiveness of Catalysis by Succinyl Coenzyme A Synthetase William A. Bridger... 

Synthetase, succinyl coenzyme A (guanosine diphosphate-forming) XXII-2... 

Figure 10.2 shows that ATP is formed by the phosphoglycerate kinase and pyruvate kinase glycolytic reactions and in the Krebs cycle by succinyl coenzyme A (CoA) synthetase in co-operation with nucleoside diphosphate kinase (Fig. 10.3). NB These reactions do...

The classical studies of Shemin [68, 69] identified glycine as one of the precursors of haem, and led to the discovery that glycine and succinyl-coenzyme A are substrates for the enzymic synthesis of 8-aminolaevulinic acid (ALA). The mitochondrial enzyme concerned, ALA-synthetase, is present in both liver and in red cell precursors [70, 71] and requires the presence of pyridoxal phosphate [72]. 

The subsequent cleavage of the thio-ester succinylCoA into succinate and coenzyme A by succinic acid-CoA ligase (succinyl CoA synthetase, succinic thiokinase) is strongly exergonic and is used to synthesize a phosphoric acid anhydride bond ( substrate level phosphorylation , see p. 124). However, it is not ATP that is produced here as is otherwise usually the case, but instead guanosine triphosphate (CTP). However, GTP can be converted into ATP by a nucleoside diphosphate kinase (not shown). 

Succinyl-CoA synthetase (GDP) [EC 6.2.1.4], also known as succinate CoA ligase, catalyzes the reversible reaction of GTP with succinate and coenzyme A to produce GDP, succinyl-CoA, and orthophosphate. The nucleotide substrate can be replaced with ITP and itaconate can substitute for succinate. 

Figure 17,13 Reaction mechanism of succinyl CoA synthetase. The reaction proceeds through a phosphorylated enzyme intermediate. (1) Orthophosphate displaces coenzyme A, which generates another energy-rich compound, succinyl phosphate. (2) A histidine residue removes the phosphoryl group with the concomitant generation of succinate and phosphohistidine. (3) The phosphohistidine residue then swings over to a bound nucleoside diphosphate, and (4) the phosphoryl group is transferred to form the nucleoside triphosphate.

Biochemical function in human metabolism. Activation of metabolites by coenzyme A while a thioester as a high-energy compound is generated. Examples acetyl CoA, succinyl-CoA, acyl-CoA-derivates. The acyl-carrier protein is a component of the fatty acid-synthetase complex. Both coenzymes transfer acyl groups. 

Next, in coupled reactions catalyzed by succinyl CoA synthetase, succinyl CoA, HP04 , and guanosine diphosphate (GDP) react to form succinate, guanosine triphosphate (GTP), and coenzyme A ... 

Fig. 5. P-NMR spectra of 0.2 mAf solution of E. coli succinyl-CoA synthetase at pH 7.2. (a) No additions, (b) Addition of 2.5 mAf CaQ2. (c) Addition of 0.12 mAf coenzyme A. (d) Addition of 0.60 mAf coenzyme A. The assignments of the resonances are as follows E-P phosphohistidine, between 4.1 and 5.3 ppm coenzyme A 3 -phosphomonoester, 3 ppm and pyrophosphodiester, 10 ppm inorganic phosphate, 2.5 ppm. From Vogel and Bridger (1982b).

Investigations of liver biopsy material for enzymes involved in lactic acidosis and ketogenesis showed normal activites of pyruvate carboxylase, citrate synthetase, isocitrate dehydrogenase, glutamate-pyruvate transaminase, reduced activity of fructose 1,6-bisphosphatase and notably reduced activity of cytosolic acetoacetyl-CoA thiolase. The latter was found to be due to altered kinetic properties of the enzyme and this was confirmed in cultured skin fibroblasts, the enzyme being much more sensitive to coenzyme A inhibition than the normal enzyme. Activity of succinyl-CoA 3-keto acid-CoA transferase was not reported. 

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