The regulation of nitrate reduction in spinach leaves

1979 ◽  
Vol 57 (10) ◽  
pp. 1155-1160 ◽  
Author(s):  
David T. Canvin ◽  
K. C. Woo
Keyword(s):  
Electron Transport ◽  
Nitrate Reduction ◽  
Electron Transport Chain ◽  
Antimycin A ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Transport Chain ◽  
Respiratory Electron Transport ◽  
Spinach Leaves

Nitrate reduction did not occur in leaves in the dark in aerobic conditions but did occur in anaerobic conditions. Nitrate reduction in leaves in the dark in aerobic conditions was observed, however, when the respiratory electron transport chain was inhibited with antimycin A but not when it was inhibited with amytal or rotenone. It would appear that NADH generated outside the mitochondria was used for nitrate reduction in the dark under anaerobic conditions. The relevance of this observation to nitrate reduction in the light is discussed.

The role of malate in nitrate reduction in spinach leaves

1980 ◽  
Vol 58 (5) ◽  
pp. 517-521 ◽  
Author(s):  
K. C. Woo ◽  
D. T. Canvin
Keyword(s):  
Nitrate Reduction ◽  
Nitrite Accumulation ◽  
Antimycin A ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Leaf Discs ◽  
Spinach Leaf ◽  
Spinach Leaves

In spinach leaf discs the accumulation of nitrite from nitrate reduction under anaerobic conditions in the light in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) was inhibited by air. The inhibition of nitrate reduction by air was reversed by antimycin A but not by rotenone or amytal. The nitrate-reducing system of DCMU-inhibited leaf discs in the light appeared similar to noninhibited leaf discs in the dark. In aerobic conditions, the addition of malate stimulated nitrite accumulation. This stimulation was unaffected by malonate. Under anaerobic conditions, malate reversed the inhibition of nitrate reduction caused by either iodoacetate or arsenite to rates similar to those observed in the dark and in the light with DCMU. Malate can apparently provide a direct source of cytosolic NADH for nitrate reduction.

Glycine Decarboxylation in Mitochondria Isolated from Spinach Leaves

1976 ◽  
Vol 3 (6) ◽  
pp. 771
Author(s):  
K.C Woo ◽  
C.B Osmond
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
Exchange Reactions ◽  
Transport Chain ◽  
Lipoamide Dehydrogenase ◽  
Mitochondrial Malate Dehydrogenase ◽  
Acid Stable ◽  
Spinach Leaves

Mitochondria isolated from spinach leaves contain at least two glycine decarboxylating systems. One system is stimulated by ADP and evidently couples to the electron transport chain. The other system, three times as active, is stimulated by NAD+ and oxaloacetate and is not coupled directly to electron transport; however, comparative studies with uncouplers and inhibitors indicate it may depend on a membrane potential generated by electron transport. In this system, the role of oxaloacetate appears to be the regeneration of NAD+, via mitochondrial malate dehydrogenase, as an electron acceptor during glycine decarboxylation. Mitochondria isolated from spinach leaves also catalyse a rapid glycine-dependent exchange of bicarbonate into acid-stable products. This reaction is stimulated by the addition of lipoamide dehydrogenase. The activity of the glycine decarboxylation and exchange reactions are irreversibly lost when mitochondria are broken. When corrections are applied to account for mitochondrial breakage, the rates of glycine decarboxylation and the exchange reaction are comparable to the rates of CO*2 evolution from leaves of C*3 plants in air. The role of these processes in vivo and relationship to other sources of CO*2 in the glycollate pathway are discussed.

Bioflavonoid effects on the mitochondrial respiratory electron transport chain and cytochromecredox state

Redox Report ◽  
1999 ◽  
Vol 4 (1-2) ◽  
pp. 35-41 ◽  
Author(s):  
H. Moini ◽  
A. Arroyo ◽  
J. Vaya ◽  
L. Packer
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
Transport Chain ◽  
Respiratory Electron Transport ◽  
Mitochondrial Respiratory

Identification of a multi-protein reductive dehalogenase complex inDehalococcoides mccartyistrain CBDB1 suggests a protein-dependent respiratory electron transport chain obviating quinone involvement

2016 ◽  
Vol 18 (9) ◽  
pp. 3044-3056 ◽  
Author(s):  
Anja Kublik ◽  
Darja Deobald ◽  
Stefanie Hartwig ◽  
Christian L. Schiffmann ◽  
Adarelys Andrades ◽  
...  
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
Reductive Dehalogenase ◽  
Transport Chain ◽  
Respiratory Electron Transport

scholarly journals Redox Regulation of Calcium Signaling in Cancer Cells by Ascorbic Acid Involving the Mitochondrial Electron Transport Chain

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Grigory G. Martinovich ◽  
Elena N. Golubeva ◽  
Irina V. Martinovich ◽  
Sergey N. Cherenkevich
Keyword(s):  
Ascorbic Acid ◽  
Electron Transport ◽  
Calcium Signaling ◽  
Electron Transport Chain ◽  
Redox Regulation ◽  
Complex Iii ◽  
Antimycin A ◽  
Ros Production ◽  
Mitochondrial Complex ◽  
Transport Chain

Previously, we have reported that ascorbic acid regulates calcium signaling in human larynx carcinoma HEp-2 cells. To evaluate the precise mechanism of Ca2+ release by ascorbic acid, the effects of specific inhibitors of the electron transport chain components on mitochondrial reactive oxygen species (ROS) production and Ca2+ mobilization in HEp-2 cells were investigated. It was revealed that the mitochondrial complex III inhibitor (antimycin A) amplifies ascorbate-induced Ca2+ release from intracellular stores. The mitochondrial complex I inhibitor (rotenone) decreases Ca2+ release from intracellular stores in HEp-2 cells caused by ascorbic acid and antimycin A. In the presence of rotenone, antimycin A stimulates ROS production by mitochondria. Ascorbate-induced Ca2+ release in HEp-2 cells is shown to be unaffected by catalase. The results obtained suggest that Ca2+ release in HEp-2 cells caused by ascorbic acid is associated with induced mitochondrial ROS production. The data obtained are in line with the concept of redox signaling that explains oxidant action by compartmentalization of ROS production and oxidant targets.

scholarly journals NoxE NADH Oxidase and the Electron Transport Chain Are Responsible for the Ability of Lactococcus lactis To Decrease the Redox Potential of Milk

2009 ◽  
Vol 76 (5) ◽  
pp. 1311-1319 ◽  
Author(s):  
Sybille Tachon ◽  
Johannes Bernhard Brandsma ◽  
Mireille Yvon
Keyword(s):  
Electron Transport ◽  
Redox Potential ◽  
Lactococcus Lactis ◽  
Growth Phase ◽  
Dairy Products ◽  
Electron Transport Chain ◽  
Anaerobic Conditions ◽  
Transport Chain ◽  
Fermented Dairy Products ◽  
Fermented Dairy

ABSTRACT The redox potential plays a major role in the microbial and sensorial quality of fermented dairy products. The redox potential of milk (around 400 mV) is mainly due to the presence of oxygen and many other oxidizing compounds. Lactococcus lactis has a strong ability to decrease the redox potential of milk to a negative value (−220 mV), but the molecular mechanisms of milk reduction have never been addressed. In this study, we investigated the impact of inactivation of genes encoding NADH oxidases (noxE and ahpF) and components of the electron transport chain (ETC) (menC and noxAB) on the ability of L. lactis to decrease the redox potential of ultrahigh-temperature (UHT) skim milk during growth under aerobic and anaerobic conditions. Our results revealed that elimination of oxygen is required for milk reduction and that NoxE is mainly responsible for the rapid removal of oxygen from milk before the exponential growth phase. The ETC also contributes slightly to oxygen consumption, especially during the stationary growth phase. We also demonstrated that the ETC is responsible for the decrease in the milk redox potential from 300 mV to −220 mV when the oxygen concentration reaches zero or under anaerobic conditions. This suggests that the ETC is responsible for the reduction of oxidizing compounds other than oxygen. Moreover, we found great diversity in the reducing activities of natural L. lactis strains originating from the dairy environment. This diversity allows selection of specific strains that can be used to modulate the redox potential of fermented dairy products to optimize their microbial and sensorial qualities.

scholarly journals Alternative splicing of coq-2 controls the levels of rhodoquinone in animals

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
June H Tan ◽  
Margot Lautens ◽  
Laura Romanelli-Cedrez ◽  
Jianbin Wang ◽  
Michael R Schertzberg ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Caenorhabditis Elegans ◽  
Electron Transport ◽  
Electron Transport Chain ◽  
Substrate Selection ◽  
Anaerobic Conditions ◽  
Parasitic Helminths ◽  
Transport Chain ◽  
Splice Forms ◽  
Electron Carriers

Parasitic helminths use two benzoquinones as electron carriers in the electron transport chain. In normoxia, they use ubiquinone (UQ), but in anaerobic conditions inside the host, they require rhodoquinone (RQ) and greatly increase RQ levels. We previously showed the switch from UQ to RQ synthesis is driven by a change of substrates by the polyprenyltransferase COQ-2 (Del Borrello et al., 2019; Roberts Buceta et al., 2019); however, the mechanism of substrate selection is not known. Here, we show helminths synthesize two coq-2 splice forms, coq-2a and coq-2e, and the coq-2e-specific exon is only found in species that synthesize RQ. We show that in Caenorhabditis elegans COQ-2e is required for efficient RQ synthesis and survival in cyanide. Importantly, parasites switch from COQ-2a to COQ-2e as they transit into anaerobic environments. We conclude helminths switch from UQ to RQ synthesis principally via changes in the alternative splicing of coq-2.

Self-assembled light-driven photosynthetic-respiratory electron transport chain hybrid proton pump

2013 ◽  
Vol 4 (10) ◽  
pp. 3833 ◽  
Author(s):  
David Hvasanov ◽  
Joshua R. Peterson ◽  
Pall Thordarson
Keyword(s):  
Electron Transport ◽  
Proton Pump ◽  
Electron Transport Chain ◽  
Transport Chain ◽  
Self Assembled ◽  
Respiratory Electron Transport
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