Succinyl coenzyme A synthetase

Succinyl coenzyme A synthetase (succinate thiokinase) catalyzes the formation of succinate and coenzyme-A, a 4-carbon metabolite, from succinyl-CoA.

Reaction

Succinyl-CoA synthetase catalyzes a reversible step in the citric acid cycle, which involves the substrate-level phosphorylation of GDP.

succinyl-CoA

succinate

Isoforms

Johnson et al. describe two isoforms of succinyl-CoA synthetase in mammals, one that specifically uses ATP for synthesis, and one that utilizes GTP. ^[1]

• EC 6.2.1.5 - ADP-forming - SUCLA2
• EC 6.2.1.4 - GDP-forming - SUCLG1, SUCLG2

The GTP form is the one more commonly used in the human citric acid cycle.^{[citation needed]}

Structure

The crystal structure of Succinyl-CoA synthetase alpha subunit (ATP-binding isoform) was determined by Joyce et al. to a resolution of 2.10 A, with PDB code 1CQJ. [1].^[2]

References

1. ^ Johnson JD, Mehus JG, Tews K, Milavetz BI, Lambeth DO (1998). "Genetic evidence for the expression of ATP- and GTP-specific succinyl-CoA synthetases in multicellular eucaryotes". J Biol Chem 273 (42): 27580–6. doi:10.1074/jbc.273.42.27580. http://www.jbc.org/cgi/content/full/273/42/27580. 
2. ^ Joyce, M. A., Fraser, M. E., James, M. N. G., Bridger, W. A., and Wolodko, W. T. (2000) Biochemistry 39, 17-25

External links

• MeSH Succinyl+Coenzyme+A+Synthetases