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Interfacial Catalysis at Oil/Water Interfaces
Published in Alexander G. Vdlkdv, Interfacial Catalysis, 2002
The active sites of many redox enzymes seem to be more or less buried within the enzyme molecules as evidenced in the case of glucose oxidase by the three-dimensional structure [44]; consequently, the direct electron transfer of the redox enzymes at an electrode seems to be difficult. It is interesting to see that a unidirectional electron flow occurs in the respiratory reaction in biological cell membranes, in which iron-sulfur clusters, flavins, quinones, and heme groups serve as electron-relaying centers. There exist flavocytochrome enzymes and/or quinocytochrome enzymes in some bacterial cell membranes, functioning as channels of electron flow from substrates to respiratory chains in the membranes. The enzymes have more than two redox centers: one is FAD or quinone cofactors, the site to accept electrons from the substrates, and the others are heme groups serving as electron-relaying centers to donate electrons to ubiquinone in the membranes. When such a membrane-bound enzyme is adsorbed on an electrode, the electrode may accept electrons from the adsorbed enzyme through the heme groups in the catalytic oxidation of the substrate.
Se, 34]
Published in Alina Kabata-Pendias, Barbara Szteke, Trace Elements in Abiotic and Biotic Environments, 2015
Alina Kabata-Pendias, Barbara Szteke
Selenium aids in the defense of oxidative stress, the regulation of thyroid hormone action, and the regulation of the redox status of vitamin C and other molecules. Its activity appears to be closely related to the antioxidative properties of α-tocopherol (vitamin E) and coenzyme Q (ubiquinone). Organic and inorganic Se compounds function is in preventing certain disease that have been, in the past, associated with vitamin E deficiency. Selenium protects the organism from oxidative damage to cell membranes by destroying H2O2, whereas vitamin E protects against damage by preventing the formation of the lipid hydroperoxides.
Abiotic Stress in Plants
Published in Hasanuzzaman Mirza, Nahar Kamrun, Fujita Masayuki, Oku Hirosuke, Tofazzal M. Islam, Approaches for Enhancing Abiotic Stress Tolerance in Plants, 2019
Ashutosh K. Pandey, Annesha Ghosh, Kshama Rai, Adeeb Fatima, Madhoolika Agrawal, S.B. Agrawal
Secondary oxidative stress development both in roots and in shoots is inevitable under prolonged flooded condition (Sairam et al., 2008; Simova-Stoilova et al., 2012). The prevention of ROS formation and the countering of oxidative damage is a highly relevant defense mechanism both during short and long-duration waterlogging stress (Colmer). Hypoxic tissues exhibited enhanced superoxide radical production from mitochondria owing to the donation of accumulated electrons at Complex III enzyme (ubiquinone: cytochrome c reductase) of the electron transport chain to O2 (Sairam et al., 2008).
The response of C/N/S cycling functional microbial communities to redox conditions in shallow aquifers using in-situ sediment as bio-trap matrix
Published in Environmental Technology, 2023
Cui Li, Rong Chen, Weiwei Ouyang, Chen Xue, Minghui Liu, Hui Liu
To further explore the changes in microbial functions in different redox conditions, the KEGG database was used to annotate the metabolic pathways predicted from 16S rRNA gene sequences. According to the changes in abundance before and after the 12-d experiment, 26 different metabolism functions of the microbes in the subpathway level are presented in Figure 5. The ubiquinone/other terpenoid-quinone biosynthesis and oxidative phosphorylation pathways are related to the electron transport activity [43]. Their abundances increased by 47 and 24 in well RE1, respectively. At the same time, only the oxidative phosphorylation pathway increased by 40 in well RE2. Both pathways decreased in well RE3 (Figure 5a). Therefore, O2 potentially enhanced electron transport activity. Biological electron transfer plays a vital role in microbial degradation of organic matter [44].
Biorefining process of agricultural onions to functional vinegar
Published in Preparative Biochemistry & Biotechnology, 2023
Xinhua Liu, Liangliang Zhang, Chunxin Cao, Jianfeng Wang, Xiaoming Sun, Jianfeng Yuan
Now vinegar manufacture usually occurs in two successive fermentation, i.e., the facultative anaerobic conversion of sugars to ethanol by yeast (alcoholic fermentation), and the aerobic oxidation of ethanol to acetic acid with acetic bacteria as the protagonist (acetic fermentation).[7,8] The molecular mechanism of oxidation of ethanol to acetic acid by acetic bacteria has been thoroughly studied, and it has been confirmed that this process is the result of joint action of membrane binding alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH) and ubiquinone oxidase, linked to the respiratory chain.[9,10] However, there is called peroxidation in this process, resulting in reducing the accumulation of acetic acid. This is mainly because acetic acid bacteria assimilate acetate and CO2via the TCA cycle to resist the acetic acid.[11]
Optimization of extraction tower structure and extraction conditions for lincomycin separation
Published in Preparative Biochemistry & Biotechnology, 2023
Jinlong Tan, Junfen Wan, Saicheng Yu, Jiaying Mao, Xuejun Cao
Compared with the ten-stage mixer-settler used in current commercial lincomycin production, the extraction rate of the turbine tower is about 10% higher than the mixer-settler, which is about 85–90% extraction rate (data from Topfond Company), and moreover, it has low energy consumption due to low stirring speed and low extraction temperature since only one electric motor needs for the tower, whereas ten electric motors need for the ten-stage mixer-settler. In addition, by replacing the mixer-settler with the extraction tower, the amount of extraction solvent could be reduced since high phase ratio could be adopted with high extraction rate; it is also convenient for automatic operation since interface, temperature and flowrate can be easily controlled automatically and accurately; and area occupied for production equipment could also be greatly reduced. So such a turbine extraction tower is expected to be applied in the production of lincomycin. The similar turbine extraction towers designed by ourselves have been applied in the separation of several fermentation products such as vitamin, ubiquinone and organic acid.