In the last reaction, catalyzed by pyruvate kinase(丙酮酸激酶), phosphoenolpyruvate transfers its phosphoryl group to ADP in another substrate-level phosphorylation.•Note that the enzyme is named as if it were acting leftward in the reaction shown below, even though it is strongly exergonic in the rightward direction. •Many enzymes were named before the function or direction of intracellular catalysis had been identified.