6.3.3.6 E380A kcat/Km is 74.3fold lower compared to wild-type value 721613 6.3.3.6 E380D retains a functional general base with a pKa of about 7.4 for kcat. The acidic region of the log (kcat/Km) versus pH profiles displays an ionizable group with a pKa of about 7.7. kcat/Km is 1.4fold lower compared to wild-type value 721613 6.3.3.6 E380Q variant displays a plateau in the acidic region. The acidic region of the log (kcat/Km) versus pH profiles becomes pH-independent for E380Q. kcat/Km is 3.8fold lower compared to wild-type value 721613 6.3.3.6 K443A at pH 8.0, 6.33 and 9.33 the mutant enzyme shows no measurable activity 721605 6.3.3.6 K443M at pH 8.0, 6.33 and 9.33 the mutant enzyme shows no measurable activity 721605 6.3.3.6 Y345A mutant exhibits a 5fold increase in Km of (2S,5S)-5-carboxymethylproline and a 165fold decrease in specificity constant compared to wild-type enzyme. kcat/Km is 165fold lower compared to wild-type value 721613 6.3.3.6 Y345A/E380A kcat/Km is 87fold lower compared to wild-type value 721613 6.3.3.6 Y345F pH-dependent kcat and kcat/Km plots retain the bell-shaped curve of wild-type CPS with similar pK values. kcat/Km is 1.7fold lower compared to wild-type value 721613 6.3.3.6 Y345F/E380D kcat/Km is 87fold lower compared to wild-type value 721613 6.3.3.6 Y345F/E380Q kcat/Km is 95fold lower compared to wild-type value 721613