scholarly journals Identification of the quinone species in cyanide-sensitive and cyanide-insensitive mitochondria of Moniliella tomentosa

1980 ◽  
Vol 192 (3) ◽  
pp. 881-885 ◽  
Author(s):  
J Vanderleyden ◽  
M Meyers ◽  
H Verachtert
Keyword(s):  
Electron Transport ◽  
Oxidase Activity ◽  
Alternative Oxidase ◽  
Transport Pathways ◽  
Naturally Occurring

Moniliella tomentosa was investigated for the presence of different quinones that might be involved in the cyanide-sensitive and/or cyanide-insensitive electron-transport pathways. The naturally occurring quinone in Moniliella tomentosa was found to be ubiquinone-45. Other quinone species could not be detected. The concentration of ubiquinone-45 in mitochondria is not related to the presence or absence of the alternative oxidase activity.

scholarly journals The Complementary Roles of Chloroplast Cyclic Electron Transport and Mitochondrial Alternative Oxidase to Ensure Photosynthetic Performance

2021 ◽  
Vol 12 ◽  
Author(s):  
Avesh Chadee ◽  
Nicole A. Alber ◽  
Keshav Dahal ◽  
Greg C. Vanlerberghe
Keyword(s):  
Electron Transport ◽  
Alternative Oxidase ◽  
Carbon Fixation ◽  
Electron Flux ◽  
Adenine Nucleotide ◽  
Cyclic Electron Transport ◽  
Transport Pathways ◽  
Production Ratio ◽  
Malate Valve ◽  
Adenine Nucleotide Pool

Chloroplasts use light energy and a linear electron transport (LET) pathway for the coupled generation of NADPH and ATP. It is widely accepted that the production ratio of ATP to NADPH is usually less than required to fulfill the energetic needs of the chloroplast. Left uncorrected, this would quickly result in an over-reduction of the stromal pyridine nucleotide pool (i.e., high NADPH/NADP+ ratio) and under-energization of the stromal adenine nucleotide pool (i.e., low ATP/ADP ratio). These imbalances could cause metabolic bottlenecks, as well as increased generation of damaging reactive oxygen species. Chloroplast cyclic electron transport (CET) and the chloroplast malate valve could each act to prevent stromal over-reduction, albeit in distinct ways. CET avoids the NADPH production associated with LET, while the malate valve consumes the NADPH associated with LET. CET could operate by one of two different pathways, depending upon the chloroplast ATP demand. The NADH dehydrogenase-like pathway yields a higher ATP return per electron flux than the pathway involving PROTON GRADIENT REGULATION5 (PGR5) and PGR5-LIKE PHOTOSYNTHETIC PHENOTYPE1 (PGRL1). Similarly, the malate valve could couple with one of two different mitochondrial electron transport pathways, depending upon the cytosolic ATP demand. The cytochrome pathway yields a higher ATP return per electron flux than the alternative oxidase (AOX) pathway. In both Arabidopsis thaliana and Chlamydomonas reinhardtii, PGR5/PGRL1 pathway mutants have increased amounts of AOX, suggesting complementary roles for these two lesser-ATP yielding mechanisms of preventing stromal over-reduction. These two pathways may become most relevant under environmental stress conditions that lower the ATP demands for carbon fixation and carbohydrate export.

Electron transport pathways for the oxidation of endogenous substrate(s) in Acidithiobacillus ferrooxidans

2006 ◽  
Vol 52 (4) ◽  
pp. 317-327 ◽  
Author(s):  
Yongqiang Chen ◽  
Isamu Suzuki
Keyword(s):  
Electron Transport ◽  
Electron Acceptor ◽  
Acidithiobacillus Ferrooxidans ◽  
Complex I ◽  
Iron Chelators ◽  
Endogenous Respiration ◽  
Sugar Alcohols ◽  
Transport Pathways ◽  
Endogenous Substrate ◽  
Transport Inhibitors

Oxidation of endogenous substrate(s) of Acidithiobacillus ferrooxidans with O2 or Fe3+ as electron acceptor was studied in the presence of uncouplers and electron transport inhibitors. Endogenous substrate was oxidized with a respiratory quotient (CO2 produced/O2 consumed) of 1.0, indicating its carbohydrate nature. The oxidation was inhibited by complex I inhibitors (rotenone, amytal, and piericidin A) only partially, but piericidin A inhibited the oxidation with Fe3+ nearly completely. The oxidation was stimulated by uncouplers, and the stimulated activity was more sensitive to inhibition by complex I inhibitors. HQNO (2-heptyl-4-hydroxyquinoline N-oxide) also stimulated the oxidation, and the stimulated respiration was more sensitive to KCN inhibition than uncoupler stimulated respiration. Fructose, among 20 sugars and sugar alcohols including glucose and mannose, was oxidized with a CO2/O2 ratio of 1.0 by the organism. Iron chelators in general stimulated endogenous respiration, but some of them reduced Fe3+ chemically, introducing complications. The results are discussed in view of a branched electron transport system of the organism and its possible control.Key words: Acidithiobacillus ferrooxidans, endogenous respiration, uncouplers, electron transport.

Anode Biofilms ofGeoalkalibacter ferrihydriticusExhibit Electrochemical Signatures of Multiple Electron Transport Pathways

Langmuir ◽  
2015 ◽  
Vol 31 (45) ◽  
pp. 12552-12559 ◽  
Author(s):  
Rachel A. Yoho ◽  
Sudeep C. Popat ◽  
Laura Rago ◽  
Albert Guisasola ◽  
César I. Torres
Keyword(s):  
Electron Transport ◽  
Transport Pathways

Palmitate increases superoxide production through mitochondrial electron transport chain and NADPH oxidase activity in skeletal muscle cells

2008 ◽  
Vol 216 (3) ◽  
pp. 796-804 ◽  
Author(s):  
Rafael Herling Lambertucci ◽  
Sandro Massao Hirabara ◽  
Leonardo dos Reis Silveira ◽  
Adriana Cristina Levada‐Pires ◽  
Rui Curi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Electron Transport ◽  
Nadph Oxidase ◽  
Oxidase Activity ◽  
Electron Transport Chain ◽  
Muscle Cells ◽  
Superoxide Production ◽  
Mitochondrial Electron Transport Chain ◽  
Nadph Oxidase Activity ◽  
Transport Chain

Inhibition of oxygen evolution by ivalin

1994 ◽  
Vol 72 (2) ◽  
pp. 177-181 ◽  
Author(s):  
Ernesto Bernal-Morales ◽  
Alfonso Romo De Vivar ◽  
Bertha Sanchez ◽  
Martha Aguilar ◽  
Blas Lotina-Hennsen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Sesquiterpene Lactone ◽  
Oxygen Evolution ◽  
Electron Flow ◽  
Atp Synthesis ◽  
Naturally Occurring ◽  
Transport Inhibitor ◽  
Proton Uptake ◽  
Key Words Oxygen

The inhibition of ATP synthesis, proton uptake, and electron transport (basal, phosphorylating, and uncoupled) from water to methylviologen by ivalin (a naturally occurring sesquiterpene lactone in Zaluzania triloba and Iva microcephala) indicates that it acts as electron transport inhibitor. Since photosystem I and electron transport from DPC to QA were not affected, while the electron flow of uncoupled photosystem II from H2O to DAD and from water to silicomolybdate was inhibited, we concluded that the site of inhibition of ivalin is located at the oxygen evolution level. Key words: oxygen evolution, ivalin, photosynthesis, sesquiterpene lactone.

scholarly journals Stimulation of the alternative oxidase of Neurospora crassa by Nucleoside phosphates

1980 ◽  
Vol 188 (1) ◽  
pp. 141-144 ◽  
Author(s):  
J Vanderleyden ◽  
C Peeters ◽  
H Verachtert ◽  
H Bertrand
Keyword(s):  
Neurospora Crassa ◽  
Oxidase Activity ◽  
Alternative Oxidase ◽  
Purine Nucleoside ◽  
Submitochondrial Particles ◽  
Fold Stimulation ◽  
Succinate Oxidase ◽  
Stimulation Of

The alternative-oxidase-mediated succinate oxidase activity of Neurospora crassa decreases drastically when mitochondria are fractionated into submitochondrial particles or treated with deoxycholate. The activity, however, can be completely restored in the presence of nucleoside 5′-monophosphates. The purine nucleoside 5′-monophosphates are more effective than the pyrimidine homologues. 5′-GMP gives a 10-fold stimulation of the alternative-oxidase-mediated succinate oxidase activity in submitochondrial particles. A comparison is made with the results obtained earlier with Moniliella tomentosa [Hanssens & Verachtert (1976) J. Bacteriol. 125, 825–835; Vanderleyden, Van Den Eynde & Verachtert (1980) Biochem. J. 186, 309–316].

The alternative oxidases: simple oxidoreductase proteins with complex functions

2013 ◽  
Vol 41 (5) ◽  
pp. 1305-1311 ◽  
Author(s):  
Luke Young ◽  
Tomoo Shiba ◽  
Shigeharu Harada ◽  
Kiyoshi Kita ◽  
Mary S. Albury ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Transport ◽  
Alternative Oxidase ◽  
Structural Features ◽  
Transport Proteins ◽  
Integral Membrane Proteins ◽  
Complex Functions ◽  
Membrane Bound ◽  
Iron Carboxylate ◽  
Electron Transport Proteins

The alternative oxidases are membrane-bound monotopic terminal electron transport proteins found in all plants and in some agrochemically important fungi and parasites including Trypansoma brucei, which is the causative agent of trypanosomiasis. They are integral membrane proteins and reduce oxygen to water in a four electron process. The recent elucidation of the crystal structure of the trypanosomal alternative oxidase at 2.85 Å (1 Å=0.1 nm) has revealed salient structural features necessary for its function. In the present review we compare the primary and secondary ligation spheres of the alternative oxidases with other di-iron carboxylate proteins and propose a mechanism for the reduction of oxygen to water.

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