3 HPr phosphorylation by HPrK/P in the presence of Pi and (A) FBP or (B) PEP. The reaction medium was as in Fig. 2 with 1 mM ATP. The reaction medium contained also: no addition (▲); 1 mM Pi (▾); 1 mM Pi and 5 mM FBP (■); 1 mM Pi and 15 mM FBP (●); 1 mM Pi and 1 mM PEP (□); 1 mM Pi and 5 mM PEP (◯). From: The HPr(Ser) kinase of Streptococcus salivarius: a hexameric bifunctional enzyme controlled by glycolytic intermediates and inorganic phosphate FEMS Microbiol Lett. 2003;224(1):67-72. doi:10.1016/S0378-1097(03)00429-4 FEMS Microbiol Lett | © 2003 Federation of European Microbiological Societies 1