The redox properties of Nicotinamide Methohalides

1953 ◽  
Vol 6 (4) ◽  
pp. 395 ◽  
Author(s):  
SJ Leach ◽  
JH Baxendale ◽  
MG Evans
Keyword(s):  
Sodium Dithionite ◽  
Potassium Ferricyanide ◽  
Cathodic Reduction ◽  
Hydrogen Ions ◽  
Hydrogen Electrode ◽  
Mercury Surface ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Colloidal Platinum ◽  
Reversible Reduction

The reversible reduction of nicotinamide methiodide and methochloride has been studied using cathodic reduction at a mercury surface, sodium dithionite, hydrogen and colloidal platinum, and various leuco-dyes. The method of cathodic reduction was the most satisfactory. Polarography showed a 2-step reduction. Macro-reductions at a mercury surface suggested dimerization of the intermediate free radical. The behaviour of dihydromethylnicotinamide towards hydrogen ions, oxygen, iodine, potassium ferricyanide, ferric iron, and various dyes has been examined. Although it is not readily oxidized by oxygen it is capable of reducing most other systems with a higher Eo?:. Two methods of estimating the reduced compound are suggested and involve (a) the potentiometric titration of potassium ferricyanide at pH 9.1 and (b) the reduction and decolourization of 2.6-dichlorophenolindophenol at pH 4.7. The oxidation-reduction potential of nicotinamide methiodide has been measured by oxidative titration of the dihydro-compound at pH 9.1 and 30�0.01 �C and found to be -0.36 � 0.02 V against the normal hydrogen electrode. The titration curve does riot show a separation of the two reduction steps. Evidence is discussed for the production of both o- and p-dihydromethylnicotinamide during reduction.

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.

Synthesis and Biological Evaluation of 7α,7α,7α,8α,8α,8α- Hexafluororiboflavin and 7α,7α,7α,8α,8α,8α-Hexafluoro-FMN

1983 ◽  
Vol 38 (9-10) ◽  
pp. 701-707 ◽  
Author(s):  
Peter Nielsen ◽  
Adelbert Bacher ◽  
Diana Darling ◽  
Mark Cushman
Keyword(s):  
Lactobacillus Casei ◽  
Reduction Potential ◽  
Biological Evaluation ◽  
Standard Hydrogen Electrode ◽  
Significant Extent ◽  
Hydrogen Electrode ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Order Of Magnitude ◽  
Synthesis And Biological Evaluation

7α,7α,7α,8α,8α,8α-Hexafluororiboflavin (4) has been prepared and its oxidation-reduction potential determined polarographically to be + 0.02 V with respect to the standard hydrogen electrode. Compound 4 does not by itself promote the growth of Lactobacillus casei. However, in the presence of low riboflavin (1) concentrations, the hexafluoro analog 4 has some growth enhancing activity. The FMN analog 7α,7α,7α,8α,8α,8α-hexafluororiboflavin 5′-phosphate (10) was also synthesized and found to bind tightly to apoflavodoxin from Megasphaera elsdenii. The dissociation constant (3.2 × 10-9m) is about one order of magnitude larger than that of FMN (1.1 × 10-10м). However, apoflavodoxin reconstituted with hexafluororiboflavin 5′-phosphate (10) has no coenzyme activity. Hexafluoro-FMN (10) was also unable to act as a coenzyme for luciferase from Photobacterium fisheri. Hexafluororiboflavin 4 did not inhibit the light riboflavin synthase from Bacillus subtilis to a significant extent {Ki> 10-4 м).

scholarly journals THE VIOLOGEN INDICATORS

1933 ◽  
Vol 16 (6) ◽  
pp. 859-873 ◽  
Author(s):  
L. Michaelis ◽  
Edgar S. Hill
Keyword(s):  
Methyl Viologen ◽  
Reduction Potential ◽  
Hydrogen Electrode ◽  
Benzyl Viologen ◽  
Normal Hydrogen Electrode ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Normal Hydrogen ◽  
Normal Potential

The tabulation gives the normal potentials of the various indicators at 30°C.; referred to the normal hydrogen electrode, the accuracy is estimated to be ±0.002 volt. Normal potentials of the viologens at 30°C.: Methyl viologen –0.446 volts Ethyl viologen –0.449 volts Betaine viologen –0.444 volts Benzyl viologen –0.359 volts Supposing some solution brings about a coloration of one of these indicators to the extent of A per cent of the maximum color, the oxidation-reduction potential of this solution is E = Eo – 0.06 log See PDF for Equation where Eo is the normal potential according to the above tabulation. This normal potential is independent of pH.

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.

Derivation of Optimum Study Factors for Samples Contaminated with Cd Using Electric/Magnetic Field and ORP

2013 ◽  
Vol 813 ◽  
pp. 519-524
Author(s):  
Sang An Ha ◽  
Jei Pil Wang
Keyword(s):  
Magnetic Field ◽  
Heavy Metals ◽  
Removal Rate ◽  
Underground Water ◽  
Liquid Electrode ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Removal Of Heavy Metals ◽  
High Removal Rate ◽  
Membrane Treatment

A purpose of the present study is to derive optimum study factors for removal of heavy metals using combined alternating current electric/magnetic field and electric membranes for the area contaminated with heavy metals in soil or underground water. ORP (Oxidation Reduction Potential) analysis was conducted to determine an intensity of tendency for oxidation or reduction of the samples contaminated with heavy metals, and electrical membrane treatment was used with adjustment of concentrations and voltages of liquid electrode (Na2SO4) to derive a high removal rate. Removal constants were analyzed to be 0.0417, 0.119, 0.1594 when the voltages were 5V, 10V, 15V, respectively, and treatment efficiency was shown to increase as the liquid electrode concentration was increased. Keywords: heavy metals, electric/magnetic field, ORP, electrical membrane

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