Observations on the Respiratory System of Rhodospirillum rubrum^*

Abstract

The respiration of Rhodospirillum rubrum has been studied with resting wild-type cells.A few experiments on "blue-green" mutant cells of RhodoDseudomonas soheroides have been performed. With succinate as substrate, rates of oxygen uptake in the dark, and in light at intensities sufficient to saturate photometabolism, are compared. Variables studied have been pH, temperature, physical manipulations (freezing and thawing, degree of anaerobiosis during harvest and storage), and concentration of various respiratory inhibitors and alcohols (narcotics). Light suppression of oxygen uptake can be considered the result of two processes, one of which is light-sensitive. Oxygen uptake in the absence of light ("dark respiration") is the sum of these two processes, "lightsensitive" plus "light-insensitive"; oxygen uptake in light ("light respiration") repre-* No. 170 in the series "Publications of the Giadu-

Electron Transport and Oxidative Phosphorylation in the Blue-green Alga Anabaena variabilis

“…Because of its relative insensitivity to cyanide and azide, the terminal oxidase in the respiratory electron chain of Anab. variabilis is probably of the cytochrome o type, as has been observed in the colourless Cyanophyta (Webster & Hackett, 1965;Biggins & Dietrich, 1968) and in the photosynthetic bacterium Rhodospirillum rubrum (Horio & Kamen, 1962). NADH oxidase is more sensitive to inhibitors of electron flow from pyridine nucleotides to quinones or cytochrome c than is NADPH oxidase.…”

“…variabilis share some common components and that this may account for the photo-inhibition of respiration observed in the blue-green algae (Brown & Webster, 1953;Jones & Myers, 1963). This explanation has been advanced by Horio & Kamen (1962) to account for this phenomenon in Rhodospirillum rubrum. In an examination of the link between respiration and photosynthetic electron flow in Anac.…”

Bacterial Cytochromes: II. Functional Aspects

“…Furthermore, antimycin A inhibits by 52-55 percent both succinate and NADH oxidases of the membrane fragments from the dark-grown ceIIs, but not at all those of the chromatophores from the light-grown ceUs (108,119,120). Since the oxygen uptake of the light-grown cells during growth is inhibited by 50-60 percent in 1 mM, but hardly at all by 0.1 mM CN- (121), it is unlikely that cytochrome C2 oxidase (cytochrome dark-oxi dase) is functional as the terminal enzyme for the oxygen uptakes (succi nate oxidase and N ADH oxidase) by the light-grown ceUs. N ADH :heme protein oxidoreductase has been purified from the light-grown cells, chro matophores (111,121 ) and from the dark-grown cells (21).…”

“…Since the oxygen uptake of the light-grown cells during growth is inhibited by 50-60 percent in 1 mM, but hardly at all by 0.1 mM CN- (121), it is unlikely that cytochrome C2 oxidase (cytochrome dark-oxi dase) is functional as the terminal enzyme for the oxygen uptakes (succi nate oxidase and N ADH oxidase) by the light-grown ceUs. N ADH :heme protein oxidoreductase has been purified from the light-grown cells, chro matophores (111,121 ) and from the dark-grown cells (21). The cnzyme activity is inhibited by 50-60 percent at 1 mM CN-, indicating that the fac tor (heme protein ?)…”

Reduction of Phenolindo-2,6-dichlorophenol in Dark and Light by the Blue-Green Alga, Anabaena variabilis

“…chloroplasts for photosynthesis or mitochondria for respiration. Hence the electron transport chains of procaryotic organisms may serve both in respiration and photosynthesis so that photosynthetic electron transport may exclude respiratory electron transfer (see Horio & Kamen, 1962).…”