scholarly journals Change of Oxidation/Reduction Potential of Solution by Metal-Reducing Bacteria and Roles of Biosynthesized Mackinawite

2011 ◽  
Vol 24 (4) ◽  
pp. 279-287 ◽  
Author(s):  
Seung-Yeop Lee ◽  
Jong-Min Oh ◽  
Min-Hoon Baik ◽  
Yong-Jae Lee
Keyword(s):  
Reduction Potential ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Reducing Bacteria ◽  
Metal Reducing Bacteria

scholarly journals In situ measurements of oxidation–reduction potential and hydrogen peroxide concentration as tools for revealing LPMO inactivation during enzymatic saccharification of cellulose

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Adnan Kadić ◽  
Anikó Várnai ◽  
Vincent G. H. Eijsink ◽  
Svein Jarle Horn ◽  
Gunnar Lidén
Keyword(s):  
Reduction Potential ◽  
Enzymatic Saccharification ◽  
The State ◽  
Enzyme Inactivation ◽  
Ex Situ ◽  
Process Economics ◽  
Complete Inactivation ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential

Abstract Background Biochemical conversion of lignocellulosic biomass to simple sugars at commercial scale is hampered by the high cost of saccharifying enzymes. Lytic polysaccharide monooxygenases (LPMOs) may hold the key to overcome economic barriers. Recent studies have shown that controlled activation of LPMOs by a continuous H2O2 supply can boost saccharification yields, while overdosing H2O2 may lead to enzyme inactivation and reduce overall sugar yields. While following LPMO action by ex situ analysis of LPMO products confirms enzyme inactivation, currently no preventive measures are available to intervene before complete inactivation. Results Here, we carried out enzymatic saccharification of the model cellulose Avicel with an LPMO-containing enzyme preparation (Cellic CTec3) and H2O2 feed at 1 L bioreactor scale and followed the oxidation–reduction potential and H2O2 concentration in situ with corresponding electrode probes. The rate of oxidation of the reductant as well as the estimation of the amount of H2O2 consumed by LPMOs indicate that, in addition to oxidative depolymerization of cellulose, LPMOs consume H2O2 in a futile non-catalytic cycle, and that inactivation of LPMOs happens gradually and starts long before the accumulation of LPMO-generated oxidative products comes to a halt. Conclusion Our results indicate that, in this model system, the collapse of the LPMO-catalyzed reaction may be predicted by the rate of oxidation of the reductant, the accumulation of H2O2 in the reactor or, indirectly, by a clear increase in the oxidation–reduction potential. Being able to monitor the state of the LPMO activity in situ may help maximizing the benefit of LPMO action during saccharification. Overcoming enzyme inactivation could allow improving overall saccharification yields beyond the state of the art while lowering LPMO and, potentially, cellulase loads, both of which would have beneficial consequences on process economics.

scholarly journals The Negative Impact of Varicocele on Basic Semen Parameters, Sperm Nuclear DNA Dispersion and Oxidation-Reduction Potential in Semen

2021 ◽  
Vol 18 (11) ◽  
pp. 5977
Author(s):  
Kamil Gill ◽  
Michal Kups ◽  
Patryk Harasny ◽  
Tomasz Machalowski ◽  
Marta Grabowska ◽  
...  
Keyword(s):  
Reduction Potential ◽  
Nuclear Dna ◽  
Study Groups ◽  
Semen Parameters ◽  
Sperm Dna Fragmentation ◽  
Control Groups ◽  
Infertile Men ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Sperm Dna

Since varicocele is so common in infertile men, this study intends to analyse the relationships between varicocele and conventional semen characteristics, sperm nuclear DNA dispersion and oxidation-reduction potential (ORP) in semen. Varicocele-positive and varicocele-negative infertile men (study groups) showed significantly lower standard sperm parameters and higher sperm DNA fragmentation (SDF) and ORP in semen than healthy volunteers and subjects with proven fertility (control groups). A lower proportion of low SDF levels (0–15% SDF) and higher incidence of high SDF levels (>30% SDF), as well as a higher prevalence of high ORP values (>1.37 mV/106 sperm/mL), were found in the study groups vs. the control groups. Moreover, infertile men had significantly lower odds ratios (ORs) for low SDF levels and significantly higher ORs for high SDF levels and high ORP. SDF and ORP were negatively correlated with sperm number, morphology, motility and vitality. Furthermore, a significant positive correlation was found between SDF and ORP. The obtained results suggest that disorders of spermatogenesis may occur in varicocele-related infertility. These abnormalities are manifested not only by reduced standard semen parameters but also by decreased sperm DNA integrity and simultaneously increased oxidative stress in semen.

scholarly journals The influence of oxidation-reduction state on the kinetic stability of pig kidney general acyl-CoA dehydrogenase and other flavoproteins

1984 ◽  
Vol 224 (2) ◽  
pp. 577-580 ◽  
Author(s):  
M Madden ◽  
S M Lau ◽  
C Thorpe
Keyword(s):  
Reduction Potential ◽  
Binding Protein ◽  
Sodium Dithionite ◽  
Egg White ◽  
Kinetic Stability ◽  
Pig Kidney ◽  
Data Support ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Electron Transferring Flavoprotein

Pig kidney general acyl-CoA dehydrogenase is markedly stabilized against loss of flavin and activity in 7.3 M-urea or at 60 degrees C upon reduction with sodium dithionite or octanoyl-CoA. Electron transferring flavoprotein is similarly stabilized, whereas egg white riboflavin-binding protein loses flavin more readily on reduction. These and other data support the anticipated correlation between the kinetic stability of the holoproteins and the oxidation-reduction potential of their bound flavins.

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