Definition
Carboxypeptidase C is a term occasionally encountered in scientific literature that appears to refer to an enzyme classified among carboxypeptidases—proteases that cleave amino acids from the C‑terminal end of peptide chains. No universally accepted enzymatic activity, EC number, or distinct biological role has been consistently documented for a protein specifically designated “Carboxypeptidase C.”
Overview
Because authoritative biochemical databases (e.g., BRENDA, UniProt, Enzyme Commission listings) do not presently list a distinct entity named Carboxypeptidase C, the term lacks a clear, widely recognized definition. In isolated reports, it may be used descriptively to denote a carboxypeptidase variant differing from the well‑characterized Carboxypeptidase A, B, or N, or to denote a provisional name for a newly identified enzyme pending formal classification.
Etymology / Origin
The name combines “carboxy‑” (referring to the carboxyl group at the peptide’s C‑terminal end) with “peptidase” (an enzyme that hydrolyzes peptide bonds). The suffix “C” follows the convention of alphabetic labeling used for related enzymes (e.g., Carboxypeptidase A, B). The designation likely originates from early attempts to categorize newly discovered carboxypeptidase activities before a systematic EC number assignment.
Characteristics
- Catalytic activity: Presumed to hydrolyze peptide bonds at the C‑terminal residue of substrate proteins or peptides, similar to other carboxypeptidases.
- Cofactor requirement: Carboxypeptidases may be metalloproteases (requiring Zn²⁺) or serine‑type enzymes; the specific cofactor for a putative Carboxypeptidase C is not documented.
- Cellular location: Unclear; analogous enzymes are found in the pancreas (secreted), lysosome (soluble), or membrane‑bound compartments.
- Molecular weight / structure: No reliable structural data are available.
- Physiological role: Not established; proposed functions in peptide processing or catabolism remain speculative.
Related Topics
- Carboxypeptidase A – a well‑characterized pancreatic Zn²⁺‑dependent exopeptidase.
- Carboxypeptidase B – a lysosomal enzyme with distinct substrate specificity.
- Carboxypeptidase N – a plasma‑borne enzyme regulating peptide hormones.
- Protease classification (EC 3.4) – the broader enzyme class encompassing carboxypeptidases.
- Enzyme Commission (EC) numbers – the systematic scheme used to assign definitive identifiers to enzymatic activities.
Note: Accurate information about a distinct enzyme named Carboxypeptidase C is not confirmed in primary biochemical reference works. The discussion above reflects the limited and ambiguous usage of the term in the literature.