Proposed mechanism for post-translational self-modification of Co-NHase based on Co2+ diffusion limitation.

The interactions of positively charged residues near the catalytic center, such as lysine with strong electrostatic repulsive interaction, arginine with weak electrostatic repulsive interaction and histidine with metal affinity, could limit the free diffusion of Co2+ in NHase and affect the efficiency of post-translational self-modification. This work also provided an effective strategy for protein engineering of NHases and other metalloenzymes.