Catalysis of a step of the overall reaction by the alpha subunit of Escherichia coli succinyl coenzyme A synthetase.

The isolated alpha subunit or succinyl-CoA synthetase from Escherichia coli is capable of catalyzing one step of the overall reaction, namely its own phosphorylation by the substrate ATP. The data presented herein also suggest that the binding sites for other substrates (succinate, succinyl-CoA) are located either on the beta subunit or comprise part of both subunit types. From these observations and from our earlier finding that the two subunits species are necessary for the overall reaction, we propose that the active site is assembled at or close to the point of contact of the two subunits in the native alpha2beta2 enzymic structure.