Glutaminyl cyclase (QC; isoform: isoQC) is a zinc-dependent enzyme that catalyzes the intramolecular cyclization of N-terminal glutamine and glutamic acid residues into pyroglutamate residue (pGlu). This conversion type posttranslational modification called pyroglutamylation. The expression QC/isoQC regulated by epigenetics, cell homeostasis, its substrates. Pyroglutamylation an important matur...