- Carboxypeptidase A
Carboxypeptidase A usually refers to the
pancreatic exopeptidasewhich hydrolyzes peptide bondsof C-terminal residues with aromaticor aliphatic side chains. Most scientists in the field now refer to this enzyme as Gene|CPA1, and to a related pancreatic carboxypeptidaseas Gene|CPA2.
In addition, there are 4 other mammalian enzymes named CPA-3 through CPA-6, and none of these are expressed in the pancreas. Instead, these other CPA-like enzymes have diverse functions.
* (also known as mast-cell CPA) is involved in the digestion of proteins by
* (previously known as CPA-3, but renumbered when mast-cell CPA was designated CPA-3) may be involved in
tumorprogression, but this enzyme has not been well studied.
* and Gene|CPA6 have also not been well studied. Interestingly, a human mutation of CPA-6 is known to cause
Duane's syndrome(abnormal eye movement). This, together with the localization of CPA-6 to embryonic eye muscle (in addition to other limited locations) suggests a role for CPA-6 in the control of neuronal migration/axonal guidance.
CPA-1 and CPA-2 (and presumably all other CPAs) contain a
zincatom at the active site. Loss of the zinc leads to loss of activity, which can be replaced easily by zinc, and also by some other divalentmetals ( cobalt, nickel).
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