Pyroglutamyl peptidase I, also known as glutaminyl cyclase or QPCT, is an enzyme that plays a crucial role in several biological processes. It is a member of the N-terminal nucleophile (Ntn) hydrolase superfamily and is primarily found in the brain tissue, although it is also present in various other organs.
The main function of pyroglutamyl peptidase I is to catalyze the conversion of N-terminal glutaminyl residues into pyroglutamate residues. This process, known as pyroglutamate formation, can be found in many bioactive peptides and neuropeptides. Pyroglutamate formation is essential for the bioactivity, stability, and receptor binding of these peptides.
In addition to its role in pyroglutamate formation, pyroglutamyl peptidase I is also involved in the generation of amyloid beta peptides, which are implicated in the pathogenesis of Alzheimer's disease. The enzyme cleaves the N-terminal glutamine residues from amyloid precursor proteins, leading to the production of amyloid beta peptides that are highly toxic and prone to aggregation.
Mutations or dysfunctions in the pyroglutamyl peptidase I gene have been associated with various neurological disorders, including Alzheimer's disease and Down syndrome.
Overall, pyroglutamyl peptidase I is an important enzyme involved in the synthesis and metabolism of bioactive peptides, as well as in the pathogenesis of neurodegenerative diseases.
