scholarly journals Electron acceptor redox potential globally regulates transcriptomic profiling in Shewanella decolorationis S12

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Yingli Lian ◽  
Yonggang Yang ◽  
Jun Guo ◽  
Yan Wang ◽  
Xiaojing Li ◽  
...  
Keyword(s):  
Redox Potential ◽  
Electron Acceptor ◽  
Transcriptomic Profiling ◽  
Shewanella Decolorationis S12

scholarly journals Titrations with ferrocyanide of japanese-lacquer-tree (Rhus vernicifera) laccase and of the type 2 copper-depleted enzyme. Interrelation of the copper sites

1980 ◽  
Vol 187 (2) ◽  
pp. 367-370 ◽  
Author(s):  
L Morpurgo ◽  
M T Graziani ◽  
A Desideri ◽  
G Rotilio
Keyword(s):  
Absorption Band ◽  
Redox Potential ◽  
Electron Acceptor ◽  
Redox State ◽  
Redox Potentials ◽  
Rhus Vernicifera ◽  
Type 3 ◽  
Limiting Value

1. Redox titrations are reported of the metal centres in Japanese-lacquer-tree (Rhus vernicifera) laccase with ferrocyanide. 2. The redox potential of Type 1 Cu was found to increase with ferrocyanide concentration up to a limiting value similar to that for the Type 1 Cu in Type 2 Cu-depleted enzyme (which is independent of ferrocyanide concentration). 3. The redox potential of the two-electron acceptor (Type 3 Cu) is also independent of ferrocyanide concentration in Type 2 Cu-depleted enzyme and lower than values reported for the native enzyme. 4. The two-electron acceptor is present in the oxidized state in the Type 2 Cu-depleted enzyme, though the latter lacks the 330 nm absorption band. 5. The redox potential of Type 2 Cu also depends on ferrocyanide concentration, at least in the presence of azide. 6. The redox potentials are affected by freezing the solutions and/or addition of azide, the latter binding to Type 2 Cu with affinity dependent on the redox state of the two-electron acceptor.

scholarly journals Geothrix fermentans Secretes Two Different Redox-Active Compounds To Utilize Electron Acceptors across a Wide Range of Redox Potentials

2012 ◽  
Vol 78 (19) ◽  
pp. 6987-6995 ◽  
Author(s):  
Misha G. Mehta-Kolte ◽  
Daniel R. Bond
Keyword(s):  
Electron Transfer ◽  
Redox Potential ◽  
Electron Acceptor ◽  
Extracellular Electron Transfer ◽  
Redox Potentials ◽  
Active Compounds ◽  
Content Type ◽  
Electron Shuttles ◽  
Redox Active ◽  
Geothrix Fermentans

ABSTRACTThe current understanding of dissimilatory metal reduction is based primarily on isolates from the proteobacterial generaGeobacterandShewanella. However, environments undergoing active Fe(III) reduction often harbor less-well-studied phyla that are equally abundant. In this work, electrochemical techniques were used to analyze respiratory electron transfer by the only known Fe(III)-reducing representative of theAcidobacteria,Geothrix fermentans. In contrast to previously characterized metal-reducing bacteria, which typically reach maximal rates of respiration at electron acceptor potentials of 0 V versus standard hydrogen electrode (SHE),G. fermentansrequired potentials as high as 0.55 V to respire at its maximum rate. In addition,G. fermentanssecreted two different soluble redox-active electron shuttles with separate redox potentials (−0.2 V and 0.3 V). The compound with the lower midpoint potential, responsible for 20 to 30% of electron transfer activity, was riboflavin. The behavior of the higher-potential compound was consistent with hydrophilic UV-fluorescent molecules previously found inG. fermentanssupernatants. Both electron shuttles were also produced when cultures were grown with Fe(III), but not when fumarate was the electron acceptor. This study reveals thatGeothrixis able to take advantage of higher-redox-potential environments, demonstrates that secretion of flavin-based shuttles is not confined toShewanella, and points to the existence of high-potential-redox-active compounds involved in extracellular electron transfer. Based on differences between the respiratory strategies ofGeothrixandGeobacter, these two groups of bacteria could exist in distinctive environmental niches defined by redox potential.

Redox Potential of the Primary Plastoquinone Electron Acceptor QAin Photosystem II fromThermosynechococcus elongatusDetermined by Spectroelectrochemistry

Biochemistry ◽  
2009 ◽  
Vol 48 (45) ◽  
pp. 10682-10684 ◽  
Author(s):  
Tadao Shibamoto ◽  
Yuki Kato ◽  
Miwa Sugiura ◽  
Tadashi Watanabe
Keyword(s):  
Photosystem Ii ◽  
Redox Potential ◽  
Electron Acceptor

scholarly journals Redox potential of the terminal quinone electron acceptor QB in photosystem II reveals the mechanism of electron transfer regulation

2015 ◽  
Vol 113 (3) ◽  
pp. 620-625 ◽  
Author(s):  
Yuki Kato ◽  
Ryo Nagao ◽  
Takumi Noguchi
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
Redox Potential ◽  
Electron Acceptor ◽  
Light Energy ◽  
Large Decrease ◽  
Difference Spectroscopy ◽  
Light Energy Conversion ◽  
First Time ◽  
Electron Transfers

Photosystem II (PSII) extracts electrons from water at a Mn4CaO5 cluster using light energy and then transfers them to two plastoquinones, the primary quinone electron acceptor QA and the secondary quinone electron acceptor QB. This forward electron transfer is an essential process in light energy conversion. Meanwhile, backward electron transfer is also significant in photoprotection of PSII proteins. Modulation of the redox potential (Em) gap of QA and QB mainly regulates the forward and backward electron transfers in PSII. However, the full scheme of electron transfer regulation remains unresolved due to the unknown Em value of QB. Here, for the first time (to our knowledge), the Em value of QB reduction was measured directly using spectroelectrochemistry in combination with light-induced Fourier transform infrared difference spectroscopy. The Em(QB−/QB) was determined to be approximately +90 mV and was virtually unaffected by depletion of the Mn4CaO5 cluster. This insensitivity of Em(QB−/QB), in combination with the known large upshift of Em(QA−/QA), explains the mechanism of PSII photoprotection with an impaired Mn4CaO5 cluster, in which a large decrease in the Em gap between QA and QB promotes rapid charge recombination via QA−.

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