glutaminyl-peptide cyclotransferase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: N-terminal L-glutaminyl-[peptide] = N-terminal 5-oxo-L-prolyl-[peptide] + NH4+. [RHEA:23652]

Glutaminyl-peptide cyclotransferase (QPCT) activity refers to the enzymatic ability to catalyze the formation of a cyclic structure called a pyroglutamate (pGlu) residue at the N-terminus of a peptide or protein. This reaction involves the removal of water from the N-terminal glutamine residue, creating a five-membered ring structure.

The pGlu residue can significantly impact the properties of the peptide, including its stability, solubility, and susceptibility to proteolytic degradation. This modification can also affect the peptide's interaction with other molecules, including receptors and enzymes.

The reaction mechanism of QPCT involves the following steps:

1. The enzyme binds to the glutamine residue at the N-terminus of the peptide.
2. The enzyme activates the glutamine residue through a series of steps that involve the formation of a covalent intermediate.
3. The activated glutamine residue undergoes intramolecular cyclization, leading to the formation of the pGlu residue.
4. The enzyme releases the cyclized peptide.

QPCT is found in various organisms, including bacteria, fungi, plants, and animals. In humans, QPCT is involved in a wide range of biological processes, including signal transduction, immune response, and neurotransmission.

The activity of QPCT is regulated by several factors, including substrate availability, pH, and the presence of cofactors. In some cases, the activity of QPCT can be modulated by post-translational modifications, such as phosphorylation.

Mutations in the QPCT gene can lead to various human diseases, including neurological disorders, cancer, and autoimmune diseases. The study of QPCT activity has significant implications for understanding the pathogenesis of these diseases and developing new therapeutic strategies.'
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Proteins (1)

Compounds (26)