代谢
乙醛脱氢酶（ALDH）的特定活性在粗匀浆、线粒体后上清液、胞浆和微粒体组分中进行了测量，使用多种内源性和外源性乙醛以及NAD+和NADP+作为辅因子。在粗匀浆中发现的全部活性可以由胞浆和微粒体活性的总和来解释。在所有组分中，使用中链长度底物己醛和壬醛时发现最高的活性。不饱和乙醛（E,E）-2,4-壬二烯醛-1-醛和反式,反式-2,4-癸二烯醛也是两个组分的良好底物，而羟基化不饱和反式-4-羟基-2-壬醛仅是微粒体组分的良好底物。短链和芳香族外源性底物的代谢速率要低得多，只有微粒体组分对乙醛、丙烯醛和苯甲醛有效。两个组分都没有代谢2,5-二羟基苯甲醛。NAD+是大多数底物的首选辅因子。胞浆组分对己醛和壬醛的表观亲和力（Km）与在大鼠中发现的一致，但这些底物的理论最大速度（Vmax）以及其他底物的特定活性比哺乳动物中发现的要低得多。生化结果提示，鲑鱼很好地适应了内源性脂质过氧化产物的解毒，但适应外源性乙醛的解毒能力较差。
Aldehyde dehydrogenase (ALDH) specific activity was measured in crude homogenates, post-mitochondrial supernatants, cytosolic and microsomal fractions of /Rainbow trout (Oncorhynchus mykiss)/ liver, using a number of endogenous and xenobiotic aldehydes and both NAD+ and NADP+ as co-factors. All the activity found in the crude homogenate could be accounted for by the sum of the cytosolic and microsomal activities. Highest activities were found with the medium chain length substrates hexanal and nonanal in all fractions. The ,-unsaturated aldehydes, (E,E)-2,4-nonadienal-1-al, and trans, trans-2,4-decadienal, were also good substrates for both fractions, while the hydroxylated , unsaturated trans-4-hydroxy-2-nonenal was a good substrate only for the microsomal fraction. Short chain and aromatic xenobiotic substrates were metabolized at much lower rates, and only the microsomal fraction was effective against acetaldehyde, acrolein, and benzaldehyde. Neither fraction metabolized 2,5-dihydroxy benzaldehyde. NAD+ was the preferred co-factor for most substrates. Apparent affinity (Km) for hexanal and nonanal in the cytosolic fraction were comparable to that found in rats, but the theoretical maximal velocity (Vmax) for these substrates, and the specific activities for the other substrates, were much lower than found in mammals. The biochemical results suggest that trout are well adapted to detoxify products of endogenous lipid peroxidation, but are poorly adapted to detoxify xenobiotic aldehydes.
来源:Hazardous Substances Data Bank (HSDB)
