Aisien S O, Walter R D
Department of Biochemical Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Federal Republic of Germany.
Biochem J. 1993 May 1;291 ( Pt 3)(Pt 3):733-7. doi: 10.1042/bj2910733.
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.
先前描述的来自肝片吸虫的多胺N-乙酰转移酶已被观察到具有另一种功能，即生物胺的乙酰化。在整个纯化过程中，生物胺、二胺和多胺的活性保持恒定比例。发现该酶的生物胺底物包括酪胺、色胺、β-苯乙胺和组胺，其Km值分别为0.12 mM、0.26 mM、0.30 mM和0.76 mM。章鱼胺、5-羟色胺和α-苯乙胺也可作为底物，尽管程度较小。生物胺乙酰化的最适pH为7.5，辅酶A对该过程有抑制作用，其Ki为5.5 microM。N-乙酰化似乎在这种吸虫的胺代谢中起主要作用。我们推测乙酰化代表寄生虫使过量胺失活的过程。
