The regenerative loop motif is a motif found in some catalysts where a loop motif that has been perturbed in a certain way hits a block then restores itself.
The most common catalyst using a regenerative loop is a replacement catalyst for the tub used in conduits such as ST42Db, PNE−6T40_SE−6T40, and HSE44T39. It works when the tub is turned into a certain block predecessor.