Van Dessel G, Lagrou A, Hilderson H J, Dierick W
UIA Laboratory for Pathological Biochemistry, Department of Medicine, University of Antwerp, Wilrijk, Belgium.
Biochim Biophys Acta. 1993 Apr 23;1167(3):307-15. doi: 10.1016/0005-2760(93)90234-z.
The enzymic conversion of dolichol into dolichoic acid has been studied in bovine thyroid subcellular fractions using [1-3H]dolichol as a substrate. The presence of conversion activity could be demonstrated in both the mitochondrial- and supernatant fractions. Investigation of cofactor requirements revealed that NAD+ was essential for reaching optimal activity. From kinetic studies Km-values of 3.5-4 microM and 0.29 mM could be calculated for, respectively, dolichol and NAD+ using the mitochondrial fraction as an enzyme source. No inhibitory effects from ethanol or pyrazole were detected suggesting that alcohol dehydrogenase is not involved in the dolichol-->dolichoate conversion as observed in a bovine thyroid mitochondrial fraction. From inhibitor studies the conversion system behaves distinctly differently from the NADP(+)-depending microsomal oxidoreductase as well as from catalase. The conversion activity in the supernatant on the other hand must be ascribed, at least partially, to a side activity of alcohol dehydrogenase.
以[1-³H]多萜醇为底物，在牛甲状腺亚细胞组分中研究了多萜醇向多萜酸的酶促转化。在线粒体组分和上清液组分中均证实存在转化活性。对辅助因子需求的研究表明，NAD⁺对于达到最佳活性至关重要。动力学研究表明，以线粒体组分作为酶源时，多萜醇和NAD⁺的Km值分别为3.5 - 4微摩尔和0.29毫摩尔。未检测到乙醇或吡唑的抑制作用，这表明在牛甲状腺线粒体组分中观察到的多萜醇→多萜酸转化过程中，乙醇脱氢酶不参与其中。抑制剂研究表明，该转化系统与依赖NADP⁺的微粒体氧化还原酶以及过氧化氢酶的行为明显不同。另一方面，上清液中的转化活性至少部分归因于乙醇脱氢酶的副活性。
