Chimeras 3, 4 and 7 are slower than either of the parent enzymes, but all exhibit the bell-shaped pH-rate profile characteristic of the PTP family (Figure ). In Table , the pH optima and kinetic constants for the chimeras are compared with their parent enzymes, and with the most active YopH-based chimera from a previous investigation. The Chimera 3 and 4 turnover rates (kcat)