Serum acetylcholinesterase possesses trypsin-like and carboxypeptidase B-like activity |
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Authors: | D H Small |
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Institution: | Department of Biochemistry, University of Melbourne, Parkville, Vic., Australia. |
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Abstract: | 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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