China 
Africa 
Explore chapters and articles related to this topic
Biooxidation and Bioreduction
Published in Volodymyr Ivanov, Environmental Microbiology for Engineers, 2020
The most common form of biological energy in cells is ATP. A large amount of free energy is released and used for different biological functions when either one or two high-energy phosphate bonds in the molecule of ATP are hydrolyzed: ATP→ADP+Pi+portionofusableenergyADP→AMP+Pi+portionofusableenergy
Mammalian Cell Physiology
Published in Anthony S. Lubiniecki, Large-Scale Mammalian Cell Culture Technology, 2018
The primary function of oxygen in a cell culture environment is to serve as the terminal acceptor of electrons in the electron transport chain (ETC). This enables cells to efficiently convert chemical energy derived from dehydrogenation reactions into high-energy phosphate bonds in the form of ATP. An insufficient supply of oxygen causes cells to switch from aerobic metabolism (respiration) to anaerobic metabolism (glycolysis), a much less efficient method of energy generation. One role of glycolysis is therefore to buffer the effects of inadequate oxygen concentrations (172). Respirationdeficient mutants, which consume little or no oxygen, have been characterized that require high glucose concentrations for growth (173–176). Growth rates of wild-type and respiration-deficient mutants were similar, suggesting that energy derived from glycolysis was sufficient, although inefficiently obtained. A total dependence on glycolysis for the provision of energy is the exception rather than the rule. Most cells, even those originating from tumor tissue, derive a significant amount of their energy from oxidative phosphorylation (177). In order to better understand the role of oxygen in cell metabolism, especially in the generation of ATP, a general overview of oxidative phosphorylation and its regulation will be discussed.
Alterations in Cellular Enzyme Activity, Antioxidants, Adenylates, and Stress Proteins
Published in Alan G. Heath, Water Pollution and Fish Physiology, 2018
The release of energy from organic foodstuffs in cells by the various metabolic processes occurs in a stepwise fashion. The energy so obtained is “stored” temporarily in high energy phosphate bonds. The term adenylates refers to the nucleotides adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP). Creatine phosphate, while being a high-energy phosphate molecule, is not a nucleotide, although it is often measured along with the adenylates. Clearly, ATP has the most energy stored in it so the relative concentrations of these adenylates reflects the energy immediately available to the cell for muscular contraction, maintenance, ionic pumping, biosynthesis etc. They also act as modulators of enzyme activity in glycolysis and the Kreb’s cycle (Atkinson, 1977). The adenylate energy charge (AEC) is the ratio of ATP + 0.5 (ADP) to total adenylate concentration in the tissue. This value can vary from 0–1. In invertebrates and microorganisms, unstressed individuals show an AEC above about 0.8, and decreases in the AEC have been useful in assessing environmental stressors in these forms (Atkinson, 1977; Ivanovici, 1980; Livingston, 1985).
Bacterial-mediated biodegradation of pentachlorophenol via electron shuttling
Published in Environmental Technology, 2019
Heba A. El-Bialy, Ola A. A. Khalil, Ola M. Gomaa
Pentachlorophenol (PCP) has been widely used in pesticides, wood preservative, resin, lubricant and dye intermediate [1]. The global production of PCPs is estimated to be 15,000 tons per year, its liberal use, accidental spills, runoffs and leakage has led to its persistence in soils, aquatic systems and groundwater. This has incited the Environmental Protection Agency (EPA) to place it among the top 11 high phenol pollutants list and encourage researchers to allocate solutions to prevent further risks to the ecosystem [2]. The dangers underlying PCP persistence is mainly toxicity to plants, animals and humans which arises from the interference of PCP with high-energy phosphate compounds required for respiration [1,3]. Although the EPA reported the maximum contaminated level was reported to be 0.01 mg/l [2], yet PCP concentration in contaminated soil varies according to the extent of usage, Zheng et al. [4] stated that it also varies among different countries. Common methods for PCP degradation includes chemical, photochemical and microbiological methods [1,5]. The later has always been considered both an eco-friendly and cost-effective bioremediation approach that is achieved via aerobic and anaerobic conditions. [6]. The presence of bacteria growing in PCP contaminated environment is usually a reflection to their ability to degrade PCP, however, microbial assisted degradation sometimes faces limitation due to PCP persistence in the soil environment, this persistence might be attributed to the low numbers of bacteria containing PCP catabolic genes [7] or due to the need for suitable environmental conditions, specific nutrients, electron donors or electron acceptors [6]. In order to implement an effective in situ PCP degradation, a novel approach is required to enhance the degradation process. For the past few years, many studies have focused on the use of electron shuttling (ES) as part of an effective bioremediation approach. ES depends on the presence of compounds (also known as redox mediators) are an integral component in the microbial electron transfer process, they act as electron carriers between electron donors, the bacterial outer membrane proteins and eventually the electron acceptor [8], they have been frequently reported to be involved in degradation of halogenated organic compounds, azo dyes, domestic wastewater treatment as well as for electricity production via microbial fuel cells [8–10]. Whether artificially added [11] or naturally produced [12], ES plays an important role in alleviating the limitation of persistent organic compounds biodegradation [8]. Augmenting the media with an ES is considered a very effective, eco-friendly and cost-effective method to enhance the bioremediation process. ES compounds such as acetate [13] and biochar can be used on their own [14] or coupled with Fe (III) [3], or nitrate and Fe(III) [1] in order to improve PCP degradation another level.
Effect of citrulline malate supplementation on muscle function and bioenergetics during short-term repeated bouts of fatiguing exercise
Published in Journal of Sports Sciences, 2022
Laura Meimoun, Émilie Pecchi, Christophe Vilmen, David Bendahan, Benoît Giannesini
The primary goal of this work was to test for the first time whether short-term CM supplementation improves oxidative metabolism throughout repeated bouts of fatiguing exercises. According to the quantitative interpretation of bioenergetics data (Kemp et al., 2015; Kemp & Radda, 1994), we have estimated the ATP production from each energy pathway in exercising muscle. We found that exercise repetition reduced the ATP production from anaerobic process in CM-treated animals but did not affect that from oxidative pathway, which leads at first glance to assumption that CM treatment does not affect the oxidative metabolism. Nevertheless, the analysis of PCr level changes provides interesting information. The intracellular PCr level is under the control of the creatine kinase (CK), an enzyme that reversibly transfers high energy phosphate from PCr to ADP to form ATP. The PCr-CK system acts to maintain ATP pool highly charged in exercising muscle, functioning as an energy buffer at the transition from rest to exercise when PCr breakdown is the only pathway for regenerating ATP (Meyer et al., 1984; Wallimann et al., 1992). With exercise prolongation, the PCr-CK system works as an energy carrier directly involved in the transport of high-energy phosphate between the sites of production (mitochondria) and utilisation (myofilaments) of ATP, which leads the PCr level to reach a steady state (Bessman & Geiger, 1981; Meyer et al., 1984; Wallimann et al., 1992). Here, the PCr cost of contraction, i.e., the rate of PCr degradation normalised to force output, was comparable in both groups in the early stage of each exercise session. However, exercise repetition increased this cost in the vehicle group whereas it was kept constant in the animals supplemented with CM. Since an increased PCr cost of contraction is associated with a reduced oxidative ATP synthesis (Korzeniewski & Zoladz, 2004; Willcocks et al., 2010), it can be extrapolated from our data that the oxidative capacity was preserved in CM animals but reduced in the vehicle group. Noteworthy, PCr consumption measured at the end of the first exercise bout was reduced in the CM group. This reduction indicates that CM might improve the energy carrier function of the PCr-CK system, hence allowing to optimize the transport of ATP produced by oxidative phosphorylation. Overall, it can be assumed from our findings that short-term CM administration is beneficial for oxidative metabolism throughout repeated moderate-intensity exercises. Our assumption is in line with previous works in our laboratory showing that the same treatment as used here improves the oxidative capacity efficiency during a single high-intensity exercise in healthy rat (Giannesini et al., 2011) and 15 days of oral supplementation with 6 g/day CM increases the rate of oxidative ATP production during a session of forearm low-intensity weightlifting in sedentary asthenic men (Bendahan, 2002).