Forms oxaloacetate, a four-carbon dicarboxylic acid source for the tricarboxylic acid cycle. oxaloacetate + phosphate = hydrogencarbonate + phosphoenolpyruvate Thermostable. Retains almost full activity after 10 min at 65 degrees Celsius. Homotetramer. The N-terminus is blocked. Belongs to the PEPCase type 1 family.