A complex containing all of the subunits required for a functional enzyme. Used to describe enzymes composed of many different protein subunits. For example, RNA polymerase holoenzyme is composed of six subunits: 2 alpha subunits, beta, beta', omega, and sigma.

The version of the E. coli RNA polymerase, subunit composition a2ßß's, that is able to recognize promoter sequences.

A catalytically active enzyme that includes cofactors.

See apoenzyme.