Carboxypeptidase


Carboxypeptidase

Carboxypeptidase (EC number 3.4.16 - 3.4.18) is an enzyme that hydrolyzes the carboxy-terminal (C-terminal) end of a peptide bond. Humans, animals, and plants contain several types of carboxypeptidases with diverse functions ranging from catabolism to protein maturation.

Functions

The first carboxypeptidases studied were those involved in the digestion of food (pancreatic carboxypeptidases A1, A2, and B). However, most of the known carboxypeptidases are not involved in catabolism; they help to mature proteins or regulate biological processes. For example, the biosynthesis of neuroendocrine peptides such as insulin requires a carboxypeptidase. Carboxypeptidases also function in blood clotting, growth factor production, wound healing, reproduction, and many other processes.

Classification

By active site mechanism

Carboxypeptidases are usually classified into one of several families based on their active site mechanism.

* Enzymes that use a metal in the active site are called "metallo-carboxypeptidases" (EC number 3.4.17).
* Other carboxypeptidases that use active site serine residues are called "serine carboxypeptidases" (EC number 3.4.16).
* Those that use an active site cysteine are called "cysteine carboxypeptidase" (or "thiol carboxypeptidases")(EC number 3.4.18).

These names do not refer to the selectivity of the amino acid that is cleaved.

By substrate preference

Another classification system for carboxypeptidases refers to their substrate preference.

* In this classification system, carboxypeptidases that have a stronger preference for those amino acids containing aromatic or branched hydrocarbon chains are called carboxypeptidase A (A for aromatic/aliphatic).
* Carboxypeptidases that cleave positively charged amino acids (arginine, lysine) are called carboxypeptidase B (B for basic).

A metallo-carboxypeptidase that cleaves a C-terminal glutamate from the peptide N-acetyl-L-aspartyl-L-glutamate is called "glutamate carboxypeptidase".

A serine carboxypeptidase that cleaves the C-terminal residue from peptides containing the sequence -Pro-Xaa (Pro is proline, Xaa is any amino acid on the C-terminus of a peptide) is called "prolyl carboxypeptidase".

Activation

Some, but not all, carboxypeptidases are initially produced in an inactive form; this precursor form is referred to as a procarboxypeptidase. In the case of pancreatic carboxypeptidase A, the inactive zymogen form, pro-carboxypeptidase A, is converted to its active form - carboxypeptidase A - by the enzyme enteropeptidase. This mechanism ensures that the cells wherein pro-carboxypeptidase A is produced are not themselves digested.

ee also

* Carboxypeptidase E
* Carboxypeptidase A

ee also

* Enzyme category EC number 3.4
* Thrombin-activatable fibrinolysis inhibitor aka plasma "carboxypeptidase" B2
* bacterial transpeptidase, an "alanine carboxypeptidase"
* bradykinin is broken down among other enzymes by "carboxypeptidase N"
* "D-Ala carboxypeptidase" is a penicillin binding proteins
* Phenylalanine might inhibit "carboxypeptidase A"

External links

*
* [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=stryer.section.1170 Protease section Stryer book '02]


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Carboxypeptidase E — Carboxypeptidase E, also known as CPE, is a human gene.cite web | title = Entrez Gene: CPE carboxypeptidase E| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene Cmd=ShowDetailView TermToSearch=1363| accessdate = ] PBB Summary section title …   Wikipedia

  • Carboxypeptidase B2 — (plasma) Rendering based on PDB 3D66 …   Wikipedia

  • Carboxypeptidase A2 — (pancreatic), also known as CPA2, is a human gene.cite web | title = Entrez Gene: CPA2 carboxypeptidase A2 (pancreatic)| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene Cmd=ShowDetailView TermToSearch=1358| accessdate = ] PBB Summary… …   Wikipedia

  • Carboxypeptidase A — usually refers to the pancreatic exopeptidase which hydrolyzes peptide bonds of C terminal residues with aromatic or aliphatic side chains. Most scientists in the field now refer to this enzyme as Gene|CPA1, and to a related pancreatic… …   Wikipedia

  • Carboxypeptidase — Carboxypeptidasen Enzymklassifikation EC, Kategorie …   Deutsch Wikipedia

  • Carboxypeptidase B — protein Name=carboxypeptidase B1 (tissue) caption= width= HGNCid=2299 Symbol=CPB1 AltSymbols= EntrezGene=1360 OMIM=114852 RefSeq=NM 001871 UniProt=P15086 PDB= ECnumber=3.4.17.2 Chromosome=3 Arm=q Band=24 LocusSupplementaryData=protein… …   Wikipedia

  • carboxypeptidase — Enzymes (particularly of pancreas) that remove the C terminal amino acid from a protein or peptide. Carboxypeptidase A, (EC 3.4.17.1) will remove any amino acid; carboxypeptidase B (EC 3.4.17.2) is specific for terminal lysine or arginine …   Dictionary of molecular biology

  • carboxypeptidase C — See serine carboxypeptidase …   Medical dictionary

  • carboxypeptidase — karboksipeptidazė statusas T sritis chemija apibrėžtis Fermentas, atskeliantis C galines aminorūgštis. atitikmenys: angl. carboxypeptidase rus. карбоксипептидаза …   Chemijos terminų aiškinamasis žodynas

  • carboxypeptidase — noun Date: 1935 an enzyme that hydrolyzes peptides and especially polypeptides by splitting off sequentially the amino acids at the end of the peptide chain which contain free carboxyl groups …   New Collegiate Dictionary