Influence of diffusion on first‐order deactivation of microheterogeneous enzyme samples

Analysis by A. Malhotra and A. Sadana examined the effects of microheterogeneity with a continuous normal distribution of thermal deactivation activation energies on first-order enzyme deactivation. Their analysis showed that even a small degree of microheterogeneity can cause a substantial change in the activity-time trajectory for an enzyme undergoing essentially first-order deactivation. A limitation on the above analysis is the absence of an analysis of diffusion effects on apparent microheterogeneity. Diffusion effects should not be ignored when one is modeling immobilized enzyme reactors, especially since diffusion effects are well known in such systems and can have a significant effect on apparent kinetics and on 'apparent microheterogeneity.' This aspect is analyzed in detail in this communication. We will carefully examine if diffusion maintains, suppresses, or exacerbates the apparent influence of microheterogeneity on enzyme deactivation.