scholarly journals The electron-transport chains of the obligate methylotroph Methylophilus methylotrophus

1980 ◽  
Vol 192 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Andrew R. Cross ◽  
Christopher Anthony
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Redox Potentials ◽  
Obligate Methylotroph ◽  
Methylophilus Methylotrophus ◽  
Cytochrome O ◽  
Cytochromes C ◽  
Band Absorption ◽  
Membrane Bound ◽  
Α Band

The cytochrome complement of Methylophilus methylotrophus and its respiratory properties were determined during batch culture and in continuous culture under conditions of methanol-, nitrogen- and O2-limitation. About 35% of the cytochrome c produced by the bacteria was released into the growth medium, and of the remaining cytochrome c about half was membrane-bound and half was soluble. Two cytochromes c were always present on membranes (redox potentials 375mV and 310mV), and these probably correspond to the soluble cytochromes c described previously [Cross & Anthony (1980) Biochem. J.192, 421–427]. A third minor component of cytochrome c (midpoint potential 356mV) was only detected on membranes of methanol-limited bacteria. M. methylotrophus always contained two membrane-bound cytochromes b with α-band absorption maxima of about 556 and 563nm (measured at room temperature) and midpoint potentials of 110 and 60mV respectively. There appeared to be relatively more of the cytochrome b563 in methanol-limited bacteria. A third b-type cytochrome with an α-band absorption maximum at 558 (at 77K) reacted with CO and had a high midpoint redox potential (260mV); it is thus a potential oxidase and hence is called cytochrome o. The roles of these cytochromes in electron transport were confirmed by investigating the patterns of respiratory inhibition. It is proposed that two cytochromes are physiological oxidases: cytochrome a+a3, which is present only in methanol-limited conditions, and the cytochrome o, which is induced 10-fold in conditions of methanol excess. Schemes for electron transport from methanol and NAD(P)H to O2 in M. methylotrophus under various limitations are proposed. Spectra and potentiometric titrations of cytochromes in whole cells and membranes of M. methylotrophus grown under various nutrient limitations have been deposited as Supplementary Publication SUP 50111 (10 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978) 169, 5.

scholarly journals The purification and properties of the soluble cytochromes c of the obligate methylotroph Methylophilus methylotrophus

1980 ◽  
Vol 192 (2) ◽  
pp. 421-427 ◽  
Author(s):  
A R Cross ◽  
C Anthony
Keyword(s):  
Molecular Weight ◽  
Isoelectric Point ◽  
Low Molecular Weight ◽  
Redox Potentials ◽  
Obligate Methylotroph ◽  
Methylophilus Methylotrophus ◽  
Midpoint Potential ◽  
Purification And Properties ◽  
Cytochromes C ◽  
Cytochrome Cl

The obligate methylotroph Methylophilus methylotrophus contains three distinct soluble cytochromes c. The major cytochromes, cytochrome cH (about 50% of the total) and cytochrome cL (about 42%), were similar in most respects to the cytochromes cH and cL of the facultative methylotroph Pseudomonas AM1 [O'Keeffe & Anthony (1980) Biochem. J. 192, 411-419]. Cytochrome cH had a high isoelectric point, a midpoint redox potential at pH 7.0 of 373 mV and a low molecular weight (8500). The cytochrome cL had a low isoelectric point, a midpoint potential of 310 mV and a molecular weight of 21,000. The third cytochrome, cytochrome cLM, was clearly distinct from cytochromes cH and cL. Like the cytochrome cL of Pseudomonas AM1, the cytochrome cL of M. methylotrophus had the lowest midpoint potential, it reacted most rapidly with methanol dehydrogenase and it combined to the greatest extent with CO. Cytochromes cH and L of M. methylotrophus differed from those from Pseudomonas AM1 in having unusually high midpoint redox potentials for non-photosynthetic bacteria and in exhibiting a split alpha-band at low temperatures.

scholarly journals The microbial metabolism of C1 compounds. The cytochromes of Pseudomaonas AM1

1975 ◽  
Vol 146 (2) ◽  
pp. 289-298 ◽  
Author(s):  
C Anthony
Keyword(s):  
Molecular Weight ◽  
Electron Transport ◽  
Cytochrome C ◽  
Isoelectric Point ◽  
Microbial Metabolism ◽  
Cytochrome O

Pseudomonas AM1 contains cytochromes a, b and c and more than one CO-binding pigment (cytochrome a3, cytochrome c and possibly a cytochrome o). The soluble cytochrome c has been purified; its isoelectric point is low and its molecular weight is 20000. This cytochrome is reduced in whole bacteria by all oxidizable substrates at rates determined by the primary dehydrogenases. A mutant lacking cytochrome c oxidizes all substrates except methanol, ethanol and methylamine; these no longer support growth. The role of cytochrome c in electron transport in Pseudomonas AM1 is discussed.

Ultrastructural Cytochemistry of Some Oxidative Enzymes

1974 ◽  
Vol 32 ◽  
pp. 322-323
Author(s):  
Arnold M. Seligman
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Succinic Dehydrogenase ◽  
Atp Synthesis ◽  
Oxidative Enzymes ◽  
Reaction Products ◽  
Inner Mitochondrial Membrane ◽  
Design And Synthesis ◽  
Membrane Bound ◽  
Membrane Bound Enzymes

The membrane-bound enzymes of the succinic oxidase chain of electron transport on the cristae of mitochondria have been the target of ultrastructural cytochemical research for a number of years. Methods for succinic dehydrogenase have been improved by the continuous design and synthesis of better tetrazolium salts. The most recent is BSPT, which is not osmiophilic, but yields an osmiophilic, lipophobic, insoluble formazan. The terminal triplet of the chain of electron transport or cytochrome oxidase, consisting of cytochrome c, a and a3 has been demonstrated very well via cytochrome c with diaminobenzidine (DAB). The localization of these two reaction products specifically on the outer surface of the inner mitochondrial membrane, lends some support to speculation concerning the mechanism of transfer of oxidative energy for ATP synthesis.

scholarly journals Photosynthetic electron transport in a cell-free preparation from the thermophilic blue-green alga Phormidium laminosum

1980 ◽  
Vol 188 (2) ◽  
pp. 351-361 ◽  
Author(s):  
A C Stewart ◽  
D S Bendall
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Green Alga ◽  
Photosynthetic Electron Transport ◽  
High Potential ◽  
O2 Evolution ◽  
Blue Green Alga ◽  
Phormidium Laminosum ◽  
A Cell ◽  
Membrane Bound

1. A cell-free preparation of membrane fragments was prepared from the thermophilic blue-green alga Phormidium laminosum by lysozyme treatment of the cells followed by osmotic shock to lyse the spheroplasts. The membrane fragments showed high rates of photosynthetic electron transport and O2 evolution (180-250 mumol of O2/h per mg of chlorophyll a with 2,6-dimethyl-1,4-benzoquinone as electron acceptor). O2-evolution activity was stable provided that cations (e.g. 10mM-Mg2+ or 100mM-Na+) or glycerol (25%, v/v) were present in the suspending medium. 2. The components of the electron-transport chain in P. laminosum were similar to those of other blue-green algae: the cells contained Pigment P700, plastocyanin, soluble high-potential cytochrome c-553, soluble low-potential cytochrome c-54 and membrane-bound cytochromes f, b-563 and b-559 (both low- and high-potential forms). The amounts and midpoint potentials of the membrane-bound cytochromes were similar to those in higher-plant chloroplasts. 3. Although O2 evolution in P. laminosum spheroplasts was resistant to high temperatures, thermal stability was not retained in the cell-free preparation. However, in contrast with higher plants, O2 evolution in P. laminosum membrane fragments was remarkably resistant to the non-ionic detergent Triton X-100.

scholarly journals Membrane-Bound Structures and Associated Electron Transport Functions of Cytochrome C

2019 ◽  
Vol 116 (3) ◽  
pp. 519a
Author(s):  
Minh D. Phan ◽  
Keel Yong Lee ◽  
Hanyu Wang ◽  
James F. Browning ◽  
Sushil K. Satija ◽  
...  
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Membrane Bound

scholarly journals CO-binding c-type cytochromes and a high-potential cytochrome c in Nitrosomonas europaea

1983 ◽  
Vol 211 (2) ◽  
pp. 503-506 ◽  
Author(s):  
D J Miller ◽  
P M Wood
Keyword(s):  
Cytochrome C ◽  
Sodium Dodecyl Sulphate ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Nitrosomonas Europaea ◽  
Redox Potentials ◽  
Cytochromes C ◽  
High Redox Potential

The purification of two soluble CO-binding cytochromes c from Nitrosomonas europaea is described. Cytochrome cCO−550 ran on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis with an apparent Mr of 32 000, whereas for cytochrome cCO−552 the apparent Mr was 16 000. Redox potentials (Em, 7) were determined as +140 and −50mV respectively. Cytochrome cCO−550 was co-purified with a cytochrome c−553, for which an unusually high redox potential of +450mV was measured. These latter components were not resolved by gel-filtration chromatography or electrophoresis under denaturing conditions.

scholarly journals The electron-transport system of mitochondria from the slime mould Physarum polycephalum

1973 ◽  
Vol 134 (3) ◽  
pp. 745-751 ◽  
Author(s):  
Roger Barnes ◽  
Emer M. Colleran ◽  
O. T. G. Jones
Keyword(s):  
Steady State ◽  
Electron Transport ◽  
Cytochrome C ◽  
Cytochrome B ◽  
Transport System ◽  
Physarum Polycephalum ◽  
Respiratory Activity ◽  
Slime Mould ◽  
Aerobic And Anaerobic ◽  
Α Band

A method is described for the preparation of mitochondria from the slime mould Physarum polycephalum; the mitochondria were not coupled. P. polycephalum mitochondria oxidized added NADH via a rotenone-insensitive pathway, but the oxidation of malate plus glutamate was rotenone sensitive; both of these substrates reduced much less cytochrome b than did succinate, in both aerobic and anaerobic steady states. Spectroscopy at 77°K separated three absorption maxima in the α-band region, at 560nm, 553nm and one at 547nm due to cytochrome c. The absorption at 553nm was increased in the aerobic steady state by the addition of 2-heptyl-4-hydroxyquinoline N-oxide, suggesting that it was due to a b-type cytochrome. All three absorption maxima appeared in the aerobic steady state after the addition of a range of substrates. The respiratory activity with different substrates and the response to inhibitors of respiration were similar to those previously described for fungus mitochondria (Weiss et al., 1970; Erickson & Ashworth, 1969). When grown under conditions of haem limitation the mitochondria contained a lower concentration of cytochromes than normal.

Cytochromes and Anaerobic Sulfide Oxidation in the Purple Sulfur Bacterium Chromatium warmingii

1983 ◽  
Vol 38 (11-12) ◽  
pp. 960-967 ◽  
Author(s):  
Ursula Wermter ◽  
Ulrich Fischer
Keyword(s):  
Molecular Weight ◽  
Cytochrome C ◽  
Elemental Sulfur ◽  
Sulfide Oxidation ◽  
Sodium Dodecylsulfate ◽  
Gel Filtration ◽  
Purple Sulfur Bacterium ◽  
Cytochromes C ◽  
Membrane Bound ◽  
Reduced State

Two soluble acidic c-type cytochromes - c' and c-552 - were isolated by ion exchange :hromatography, gel filtration and ammonium sulfate fractionation. Cytochrome c' is a high-spir tochrome with maxima at 399 nm. 490 nm. and 634 nm in the oxidized form and at 550 nm. 15 nm and a characteristic shoulder at 434 nm in the reduced state. The best purity index obtained A280/A399) was 0.35. Cytochrome c' is autoxidizable, has a molecular weight of 12 000 (estimate by sodium dodecylsulfate electrophoresis), a midpoint redoxpotential of + 10 mV and an iso­electric point at pH 4.0. The reduced cytochrome c' reacts with carbon monoxide. The reaction reversible. Cytochrome c-552 shows maxima at 552 nm, 523 nm and 417 nm in the reduced for ind at 408 nm in the oxidized state. The best purity index obtained (A280/A408) was 0.94. "ytochrome c-552 has a molecular weight of 30 000 and an isoelectric point between pH 4.1 Zhromatium warmingii also contains a membrane-bound cytochrome c-552. During anaerobic sulfide oxidation, elemental sulfur and sulfate were formed at the same time. When all sulfide consumed by the cells, the remaining intracellular elemental sulfur was further oxidized to sulfate

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