Serum acetylcholinesterase possesses trypsin-like and carboxypeptidase B-like activity.
Acetylcholinesterase (AChE, EC 3.1.1.7) purified from the electric organ of eel possesses a protease activity resembling that of a neuropeptide processing enzyme. To examine whether any mammalian AChEs possess a similar protease activity, the enzyme was purified, 110,000-fold from foetal bovine serum. Purified serum AChE cleaved 2 synthetic peptide substrates in a manner resembling the combined actions of trypsin-like and carboxypeptidase B-like enzymes. A synthetic fragment of preproenkephalin A (residues 97-107) containing a complete methionine-enkephalin sequence was cleaved by serum AChE to yield free methionine-enkephalin. The carboxypeptidase action of AChE was weakly stimulated by the presence of 100 microM CoCl2 suggesting the requirement of a metal ion for complete activity. The results support the hypothesis that in many tissues AChE may act as a neuropeptide processing enzyme.
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Department of Biochemistry, University of Melbourne, Parkville, Vic., Australia.
D000110:Acetylcholinesterase / Q000097:blood*; D000818:Animals; D043424:Carboxypeptidase B; D002268:Carboxypeptidases / Q000378:metabolism*; D002417:Cattle; D004524:Eels; D004745:Enkephalins / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism*
D004745:Enkephalins; D010446:Peptide Fragments; D011498:Protein Precursors; C033660:preproenkephalin; D000110:Acetylcholinesterase; D002268:Carboxypeptidases; D043424:Carboxypeptidase B; D014357:Trypsin