Ellis J E, Setchell K D, Kaneshiro E S
Department of Biological Sciences, University of Cincinnati, OH 45221-0006.
Mol Biochem Parasitol. 1994 Jun;65(2):213-24. doi: 10.1016/0166-6851(94)90073-6.
Ubiquinone (coenzyme Q, CoQ) was analyzed and individual homologues quantified in 11 species of parasitic and free-living protozoa by a combination of thin-layer chromatography and high performance liquid chromatography. Fast atom bombardment ionization-mass spectrometry was used for the first time to confirm the identity of the fractionated CoQ homologues and proved to be a fast, gentle and convenient method for ubiquinone identification. Ubiquinone was detected in all organisms including those devoid of identifiable mitochondria. However, significantly lower levels of CoQ were present in those organisms lacking this respiratory organelle (5- to 50-fold lower in Entamoeba histolytica (CoQ9) and 15- to 350-fold for Giardia lamblia (CoQ9) and Tritrichomonas foetus (CoQ10)). Coenzyme Q9 was the predominant homologue in promastigotes of Leishmania donovani and Leishmania major. Lower amounts of CoQ8 and CoQ10 were also detected in L. donovani, and CoQ8 in L. major. Comparison of the in vitro cultivated promastigote and amastigote forms of Leishmania pifanoi and Leishmania amazonensis revealed CoQ9 to be the sole detectable ubiquinone homologue in the amastigote (macrophage) stage, whereas CoQ8 and CoQ10 were also present in the promastigotes (life cycle stage found in the insect gut) of L. pifanoi, and CoQ7 and CoQ8 in promastigotes of L. amazonensis. Interestingly, the total amounts of CoQ were similar in both forms of these organisms. The free-living ciliates, Tetrahymena thermophila and Paramecium tetraurelia contained CoQ8 as the predominant ubiquinone species and this homologue was also present in the isolated cilia from P. tetraurelia. The marine ciliate, Parauronema acutum contained CoQ7 as well as CoQ8. Comparison of xenosome-containing P. acutum with organisms lacking the symbiont revealed that twice the level of CoQ8 was present in cells grown with this cytoplasmic gram-negative bacterium. Results suggest that CoQ is ubiquitous amongst the protozoa, regardless of the presence of mitochondria, and may function in alternative roles to that of mitochondrial electron transport chain component.
通过薄层色谱法和高效液相色谱法相结合的方法，对11种寄生性和自由生活的原生动物中的泛醌（辅酶Q，CoQ）进行了分析，并对各个同系物进行了定量。首次使用快原子轰击电离质谱法来确认分离出的CoQ同系物的身份，结果证明这是一种快速、温和且方便的泛醌鉴定方法。在所有生物体中都检测到了泛醌，包括那些没有可识别线粒体的生物体。然而，在那些缺乏这种呼吸细胞器的生物体中，CoQ的水平明显较低（溶组织内阿米巴（CoQ9）低5至50倍，贾第虫（CoQ9）和胎儿三毛滴虫（CoQ10）低15至350倍）。辅酶Q9是杜氏利什曼原虫和硕大利什曼原虫前鞭毛体中的主要同系物。在杜氏利什曼原虫中还检测到少量的CoQ8和CoQ10，在硕大利什曼原虫中检测到CoQ8。对皮氏利什曼原虫和亚马逊利什曼原虫体外培养的前鞭毛体和无鞭毛体形式进行比较，发现CoQ9是无鞭毛体（巨噬细胞）阶段唯一可检测到的泛醌同系物，而CoQ8和CoQ10也存在于皮氏利什曼原虫的前鞭毛体（在昆虫肠道中发现的生命周期阶段）中，CoQ7和CoQ8存在于亚马逊利什曼原虫的前鞭毛体中。有趣的是，这些生物体两种形式中的CoQ总量相似。自由生活的纤毛虫嗜热四膜虫和双小核草履虫含有CoQ8作为主要的泛醌种类，这种同系物也存在于从双小核草履虫分离出的纤毛中。海洋纤毛虫尖锐拟阿脑虫含有CoQ7以及CoQ8。将含有异形体的尖锐拟阿脑虫与缺乏共生体的生物体进行比较，发现与这种胞质革兰氏阴性细菌一起生长的细胞中CoQ8的水平是原来的两倍。结果表明，无论线粒体是否存在，CoQ在原生动物中普遍存在，并且可能发挥线粒体电子传递链组分以外的其他作用。
