Does it have anything to do with active enzymes or substrates?

Those studies showed that each active enzyme contains two catalytic pockets.

This sequencing protects the most active enzymes, which are in the last reactors.

The specific activity should then be expressed as μmol min mg active enzyme.

Under the right conditions in solution these fragments can spontaneously reassemble to form the active enzyme.

So we represent the active enzyme as a powerful reactant of the enzymatic reaction.

This reaction by hydrogenase, an enzyme only active in the absence of oxygen, is short-lived.

Folding the expressed fusion protein gives an active enzyme.

Apoenzymes becomes active enzymes on addition of a cofactor.

This is a membrane-bound enzyme optimally active at neutral pH.