Manganese phosphoenolpyruvate

This manganese-dependent enzyme [EC 2.7.9.2], also known as phosphoenolypyruvate synthase, catalyzes the reaction of ATP with pyruvate and water to produce AMP, phosphoenolpyruvate, and orthophosphate. 

Pyruvate may enter the Krebs cycle by a pathway different from that involving the formation of acetyl-CoA. Indeed, the keto acid can be converted to a dicarboxylic acid by at least two different biochemical processes. One of them involves the carboxylation of pyruvic acid leading to the formation of oxaloacetic acid. The actual substrate in that reaction is not pyruvic acid, but phosphoenolpyruvic acid. The enzyme involved requires manganese, and IDP acts as the phosphorus acceptor. The reaction is coupled with the pyrophosphate transfer (catalyzed by nucleoside diphosphokinase) from ITP to ADP. 

The correlation between CA formation and manganese limitation in A. niger was studied through transcriptome and proteome profiling. Beside the three already described responses, two novel responses were observed, including strong down regulation of phosphoenolpyruvate carboxykinase (PEPCK) and two cation transporters. ... 

---