Respiratory Chain of Colorless Algae I. Chlorophyta and Euglenophyta

Abstract

Since relatively little is known of the respiratory chain in algae, this study was undertaken using colorless algae to avoid interference from photosynthetic pigments. Whole cell difference spectra of Prototheca zopfii, Polytoma uvella, and Polyto-mella agilis revealed the presence of cytochromes b, c, and a-a3. An excess of b-type cytochromes was revealed by low temperature (-190[degree]) and by antimycin difference spectra. Particles sedimenting at 10,000 x g and possessing high cytochrome c oxidase and NADH oxidase activities were isolated from P. zopfii and P. uvella. These properties and the presence of cytochromes in amounts characteristic of higher plant mitochondria indicated that these particles were algal mitochondria. Carbon monoxide difference spectra of both the whole cells and the particles revelaed the presence of an additional carbon monoxide-binding pigment besides cytochrome oxidase. All the data suggest that the green algae have a respiratory chain essentially identical to that of higher plants. Low temperatre difference spectra of Astasia longa were very complex in the a-region for b and c-type cytochromes. The appearance of these spectra was quite unlike similar spectra of higher plants. Also, the position and shape of the a-band for the a-type cytochrome differed from similar spectra of the green algae and higher plants. Furthermore, mitochondria isolated from Astasia were unable to oxidize reduced mammalian cytochrome c.