Biogenic-amine acetylation: an additional function of the N-acetyltransferase from Fasciola hepatica.
The previously described polyamine N-acetyltransferase from Fasciola hepatica has been observed to have an additional function, the acetylation of biogenic amines. The activities for biogenic amines, diamines and polyamines were in a constant ratio throughout the purification process. Biogenic amines found to be substrates for the enzyme included tyramine, tryptamine, beta-phenylethylamine and histamine, with Km values of 0.12 mM, 0.26 mM, 0.30 mM and 0.76 mM respectively. Octopamine, 5-hydroxytryptamine and alpha-phenylethylamine were also acceptable as substrates, though to a lesser degree. The optimum pH for biogenic-amine acetylation was 7.5, and CoA was inhibitory to the process, with a Ki of 5.5 microM. N-Acetylation appears to play a major role in the amine metabolism of this trematode. We presume that acetylation represents the process by which the parasite inactivates excess amines.
Aisien
S O
SO
Department of Biochemical Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Federal Republic of Germany.
Walter
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RD
D000107:Acetylation; D000123:Acetyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005210:Fasciola hepatica / Q000201:enzymology*; D006632:Histamine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010627:Phenethylamines / Q000378:metabolism; D013379:Substrate Specificity; D014363:Tryptamines / Q000378:metabolism; D014439:Tyramine / Q000378:metabolism
D010627:Phenethylamines; D014363:Tryptamines; C029261:phenethylamine; C030820:tryptamine; D006632:Histamine; D000123:Acetyltransferases; C030992:polyamine N-acetyltransferase; D014439:Tyramine