Molecular properties of cytochrome c oxidase in Ascaris respiratory chain and its response to oxygen tension

1. 1998年的成就：在从需氧生长的线虫中分离的线粒体中表征了秀丽隐杆线虫的呼吸链。线虫线粒体含有泛醌-9作为主要组分和玫瑰醌-9作为次要组分。泛醌-9/玫瑰醌-9比值在C.线虫线粒体比猪蛔虫第二阶段幼虫的线粒体，猪肠道寄生线虫的自由生活阶段。单个氧化还原酶活性（包括琥珀酸氧化酶）和底物可还原的细胞色素的量与A. suum。富马酸还原酶的比活性在C. elegans的线粒体比A. suum，但仍高于哺乳动物线粒体。这些结果表明，自由生活的线虫C。与需氧哺乳动物物种不同，秀丽隐杆线虫能够合成玫瑰醌，尽管它的线粒体比A.猪幼虫期2. 1999年的成就：猪蛔虫幼虫复合体II的IP亚基的特征在于，北方杂交表明成虫IP也在幼虫中表达。幼虫复合物II的IP被识别的抗体对成人IP，并从成人IP的肽图谱难以区分。通过DEAE-cellulofine柱层析纯化的幼虫复合物II中的IP的N-末端42个氨基酸序列与成虫IP的成熟形式相同。此外，在PVDF膜上的微量分析测定的幼虫IP的氨基酸组成几乎是相同的成年IP。这些结果表明，这两种不同阶段特异性形式的A。猪复合物II共享一个共同的IP亚基，即使成人酶的功能作为延胡索酸还原酶，而幼虫酶作为琥珀酸脱氢酶。

1.Achievement in l998: The respiratory chain of Caenorhabditis elegans was characterized in mitochondria isolated from aerobically grown nematodes. Nematode mitochondria contain ubiquinone-9 as a major component and rhodoquinone-9 as a minor component. The ratio of ubiquinone-9/rhodoquinone-9 is higher in C. elegans mitochondria than in mitochondria from second-stage larvae of Ascaris suum, the free-living stage of porcine gut-dwelling nematode. The individual oxidoreductase activities comprising succinate-oxidase and the amount of substrate-reducible cytochromes are comparable to those of mitochondria from second-stage larvae of A. suum. The specific activity of fumarate reductase is lower in C. elegans mitochondria than in mitochondria from second-stage larvae of A. suum, but still higher than in mammalian mitochondria. These results indicate that the free-living nematode C. elegans is capable of synthesizing rhodoquinone, as distinguished from aerobic mammalian species, although its mitochondria appear more aerobic than A. suum larval mitochondria.2. Achievement in 1999: The Ip subunit of Ascaris suum larval complex II was characterized because Northern hybridization showed that the adult Ip also is expressed in the larvae. The Ip of larval complex II was recognized by the antibody against adult Ip, and was indistinguishable from the adult Ip by peptide mapping. The N-terminal 42 amino acid sequence of Ip in the larval complex II purified by DEAE-cellulofine column chromatography was identical to that of the mature form of the adult Ip. Furthermore, the amino acid composition of larval Ip determined by micro-analysis on a PVDF membrane is almost the same as that of adult Ip. These results suggest that the two different stage-specific forms of the A. suum complex II share a common Ip subunit, even though the adult enzyme functions as a fumarate reductase, while larval enzyme acts as a succinate dehydrogenase.