aminopeptidázy

aminopeptidázy (aminopeptidases) are a broad class of proteolytic enzymes that catalyze the hydrolytic removal of single amino acid residues from the N‑terminus of peptides and proteins. They function by coordinating a divalent metal ion, usually zinc or cobalt, in a catalytic site that activates a water molecule for nucleophilic attack. The reaction proceeds with the cleavage of the amide bond immediately adjacent to the N‑terminus, generating an amino acid product and a shortened peptide chain with a new N‑terminus.

Biochemically, aminopeptidases are divided into several families based on sequence similarity and structural motifs. The M1 family includes leucine aminopeptidase and gluzincin enzymes, which have an L‑x‑H motif and are involved in metabolic processing of hormones and neuropeptides. The M17 family comprises leucyl aminopeptidases, which are hexameric cytosolic enzymes involved in nitrogen recycling. The M18 family contains methionine aminopeptidases that excise N‑terminal methionine from newly synthesized proteins. Separate groups such as the Xaa‑Xaa‑Lys/Arg aminopeptidases (Xaa‑Xaa‑K/R) and metallo-β‑lactamase‑like aminopeptidases play specialized roles in bacterial pathogenesis and adaptive immunity.

In physiology, aminopeptidases regulate signaling pathways by activating or deactivating peptide hormones, processing cytokines, and generating bioactive fragments from larger precursors. In humans, defects in specific aminopeptidases contribute to diseases such as congenital Neutrophilic Leukocyte Adhesion Deficiency type 3, Alzheimer's disease, and metabolic disorders.

Industrially, aminopeptidases are exploited for the selective hydrolysis of protein feedstocks, bioremediation of peptides in waste streams, and the synthesis of chiral amino acids. Inhibitors such as bestatin, amastatin, and various synthetic hydroxamic acids are employed both as research tools and therapeutic leads to modulate enzyme activity in cancer and inflammatory diseases.