Moser D, Nicholls P, Wastyn M, Peschek G
Institute of Physical Chemistry, University of Vienna, Austria.
Biochem Int. 1991 Jul;24(4):757-68.
Cytochromes c6 from three cyanobacteria were tested as substrates for membranous cyt. c oxidase(aa3) of Anacystis and Synechocystis using intact spheroplasts or isolated plasma(CM) and thylakoid(ICM) membranes. Neither spheroplasts nor CM/ICM gave significant O2 uptake rates with NADH without added cyt. c. Horse cyt. c (at low ionic strength) or cyt. c6 from Anacystis, Synechocystis or Microcystis (at high ionic strength) supported substantial HCN- & CO-sensitive NADH oxidase activity, consistent with in vivo O2 uptake. Cyanobacterial respiratory electron transport involves NADH dehydrogenase(fpN), plastoquinone, cyt. b/c(f), cyt. c6 & cyt. aa3, in both CM & ICM. In ICM, fpN and cyt. aa3 are functionally replaced in the light by PS II and PS I, respectively. In both membranes, cyt. c6 is an obligatory electron donor to cyt. aa3 &/or to P700. Respiratory action of acidic cyt. c6 (in unicellular species) may be unmasked only under conditions of elevated ionic strength.
使用完整的原生质球或分离的质膜（CM）和类囊体膜（ICM），测试了三种蓝细菌的细胞色素c6作为集胞藻和聚球藻膜状细胞色素c氧化酶（aa3）的底物。在不添加细胞色素c的情况下，原生质球或CM/ICM用NADH都不会产生显著的氧气摄取率。马细胞色素c（在低离子强度下）或集胞藻、聚球藻或微囊藻的细胞色素c6（在高离子强度下）支持大量对HCN和CO敏感的NADH氧化酶活性，这与体内氧气摄取一致。蓝细菌呼吸电子传递在CM和ICM中都涉及NADH脱氢酶（fpN）、质体醌、细胞色素b/c（f）、细胞色素c6和细胞色素aa3。在ICM中，fpN和细胞色素aa3在光照下分别被光系统II和光系统I功能性取代。在这两种膜中，细胞色素c6是细胞色素aa3和/或P700的必需电子供体。酸性细胞色素c6（在单细胞物种中）的呼吸作用可能仅在离子强度升高的条件下才会显现出来。
