What characterizes pseudoirreversible inhibitors?

Pseudoirreversible inhibitors are characterized by their strong affinity for an enzyme, which makes them difficult to displace even if they do not form a permanent bond. These inhibitors bind to the enzyme non-covalently but with such high binding strength that the complex remains stable for a significant time period. This means that, while they may eventually dissociate from the enzyme, the rate of dissociation is slow, effectively leading to a prolonged inhibition of the enzyme activity.

This long-lasting inhibition is a crucial feature that distinguishes pseudoirreversible inhibitors from reversible inhibitors, which can easily dissociate and restore enzyme activity. The strong binding affinity is what makes it challenging to remove these inhibitors from the enzyme's active site, which is why they are noted for their difficult displacement.

The other choices clarify aspects of inhibitors but don't accurately describe the nature of pseudoirreversible inhibitors. For instance, the notion that they bind permanently to the enzyme or have low affinities is inconsistent with their defining characteristics. Additionally, saying they do not affect enzyme activity contradicts the premise of being an inhibitor, as inhibiting an enzyme implies a reduction or total halt in its activity.