Study on Serotonine Metabolism in Fish

研究了与5-羟色胺途径有关的几种酶在鱼类体内的分布和性质。此外，还对矩阵分析方法进行了探讨。Triptophan羟基酶：这种酶在鱼的肝脏中活性较高，而据报道，在哺乳动物的脑组织中活性较高。然而，这种活动因鱼类种类而异。该酶的相对分子质量为29万(齐聚物)，最适pH为8.0，色氨酸的Km值为7.0×10~(-5)~(-5)M。芳香族氨基酸脱羧酶：该酶的相对分子质量为22万(二聚体)，最适pH为7.0，对羟基托氨酸的Km为6.97×10~(-4)&gt；M，底物专一性较广。单胺氧化酶：鱼体内存在两种类型的酶，无机离子激活和抑制的方式各不相同。代谢物分析方法：建立了5-羟色胺途径代谢物的高效液相分析系统。条件如下：(A)反相，JASCO sil C18柱，(B)流动相，10 mM醋酸钠-乙腈混合溶液，(C)流速，1ml/min，(D)监视器，荧光，Ex 285 nm，Em 345 nm。通过改变乙酸乙酯溶液和乙腈的比例，我们能够定量测定代谢物(每种化合物2-12 ng)。

Distribution and properties of several enzymes which are involved in serotonine pathway in fish were investigated. The method of matabolte analysis was also examined.1. Triptophan hydroxylase : Higher activity of this enzyme was observed in fish liver, whileitwas reported that the activity is high in brain tissue in mammals. However, the activity varied depending on fish species. The molecular weight of the skipjack enzyme was 290,000(oligomer), the optimum pH was 8.0, and Km for tryptopha was 7.0 x 10^<-5>M.2. Aromatic amino acid decarboxylase : The moleclar weight of the skipjack enzyme was 220,000(dimer), the optimum pH was 7.0, and Km for hydroxytroptohan was 6.97 x 10^<-4>M.The substrate specificity was rather wide.3. Monoamine oxidase : There were 2 types of the enzyme in fish, and the patern of the activation and inhibition by inorganic ions differed each other.4. Method of metabolite analysis : HPLC system for analysis of metabolites in serotonine pathway was examined. The condition was as follows : (a) reverse phase, JASCO SIL C18 coolumn, (b) mobile phase, a mixture of 10mM sodium acetate soltion and acetonitrile, (c) flow rate, 1ml/min, (d) monitor, fluoressence, Ex 285 nm, Em 345 nm. By changing the ratio of actate solution and acetonitrile, we were able to determine the metabolites quantitatively (2 - 12 ng of each compound).