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Movement Control (Muscular Physiology)
Published in Emeric Arus, Biomechanics of Human Motion, 2017
Two other proteins are part of the actin filaments, tropomyosin and troponin. During muscle contraction, Ca2+ and high-energy chemical compounds, such as ATP, ADP, and inorganic phosphate (Pi), have the leading role. ADP is produced when ATP is hydrolyzed (broken down) and used as a substrate in reactions producing ATP. The transfer of the ATP, ADP, and Pi happens in the mitochondria. ATP binds to a myosin head and forms ADP and Pi. When ADP and Pi are released, the actin filament sliding motion occurs over the myosin. Below are the phases of muscle contraction:ATP binds to a myosin head and forms ADP and Pi. The ADP and Pi remain attached to the myosin head.
Microbial Metabolism
Published in Maria Csuros, Csaba Csuros, Klara Ver, Microbiological Examination of Water and Wastewater, 2018
Maria Csuros, Csaba Csuros, Klara Ver
ATP is generated by direct transfer of a high energy phosphorus group from a phosphorylated compound to ADP. The following example shows only the carbon (C) skeleton and the high energy phosphorus (P) of a typical substrate.
Applications of Chemical Kinetics in Environmental Systems
Published in Kalliat T. Valsaraj, Elizabeth M. Melvin, Principles of Environmental Thermodynamics and Kinetics, 2018
Kalliat T. Valsaraj, Elizabeth M. Melvin
The complete oxidation of glucose should liberate 38 molecules of ATP, equivalent to the free energy available in glucose. If that much has to be accomplished the electrons generated during the process should be stored in other compounds that then undergo reduction. “Electron acceptors” generally used by microbes in our natural environment include oxygen, nitrate, Fe(III), SO42−, and CO2. It is to mediate the transfer of electrons from substrate to electron acceptors that the microorganisms need intermediate electron transport agents. These agents can also store some of the energy released during ATP synthesis. Some examples of these intermediates are cytochromes and iron-sulfur proteins. The same function can also be performed by compounds that act as H+-carriers (e.g., flavoproteins). The redox potentials of some of the electron transport agents commonly encountered in nature are given in Table 4.17. Chappelle (1993) cites the example of E. coli that uses the NADH/NAD cycle to initiate redox reactions that eventually releases H+ ions out of its cell. The NADH oxidation to NAD in the cytoplasm is accompanied by a reduction of the flavoprotein that releases H+ from the cell to give an FeS protein, which further converts to flavoprotein via acquisition of 2H+ from the cytoplasm and in concert with coenzyme Q releases 2H+ out of the cell. The resulting cytochrome b transfers the electron to molecular oxygen forming water. The net result is the use of the energy from redox reactions to transport hydrogen ions out of the cell. The energy accumulated in the process is utilized to convert ADP to ATP. The entire sequence of events is pictorially summarized in Figure 4.52 and is sometimes called “chemiosmosis,” the process of harnessing energy from electron transport. More details of these schemes are given in advanced textbooks such as Schlegel (1992). The main point of this discussion is the part played by electron transport intermediates and ATP synthesis in the metabolic activities of a living cell. Thus microorganisms provide an efficient route by which complex molecules can be broken down. The entire process is driven by the energy storage and release capabilities of microorganisms that are integral parts of their metabolism.
Adenosine triphosphate (ATP) bioluminescence-based strategies for monitoring atmospheric bioaerosols
Published in Journal of the Air & Waste Management Association, 2022
Yueqi Zhang, Bing Liu, Zhaoyang Tong
The use of adenylate kinase (ADK) and pyruvate kinase for ATP amplification has the potential to detect very low levels of ATP without the use of photon detectors. Lee et al. (2017) designed ATP amplification using (i) ADK as the first enzyme that converts AMP+ATP to two ADP molecules, and (ii) polyP kinase (PPK) as the second enzyme that converts ADP to ATP using polyP. In this reaction, excess AMP and polyP are added to the reaction mixture, which drives the ADK and PPK equilibriums to ADP and ATP formation, respectively. The amplified ATP is subjected to bioluminescence detection in a firefly luciferase reaction. The sensitivity of this method to ATP was about 10,000 times that of the bioluminescence method without ATP amplification. The ATP is amplified before the bioluminescence detection, and the luminescence amount can be improved without signal integration, thereby greatly improving the sensitivity of the bioluminescence detection to ATP.
Microbial fuel cells: a sustainable solution for bioelectricity generation and wastewater treatment
Published in Biofuels, 2019
Har Mohan Singh, Atin K. Pathak, Kapil Chopra, V.V. Tyagi, Sanjeev Anand, Richa Kothari
Microorganisms can use a wide spectrum of organic compounds (carbohydrates, proteins, lipids) as carbon and energy sources. These compounds can perform as electron donors in citric acid chain reactions and form energy carrier adenosine triphosphate (ATP) molecules before cyclic chain reactions. The conglomerated carbohydrates, proteins and lipids break into their constituting monomers and form acetyl coenzyme A (CoA) by glycolysis. The CoA molecule initiates the citric acid cycle and oxidation reactions occur jointly with reduction of nicotinamide adenine dinucleotide (NAD+) and flavin adenine dinucleotide (FAD) and form nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH2) as electron carriers. The citric acid cycle is completed in the cytoplasm and cell membrane with the assistance of electron carriers NADH and FADH2 (Figure 2). The cell membrane passes to terminal electron acceptor through various complex membrane intermediates and ATP synthase transmembrane protein is used to convert adenosine diphosphate (ADP) to ATP. These ATP molecules act as the chemical currency of living organisms and the production process represents respiration. In the anodic compartment, a bacterial cell replaces an electrode as the terminal electron acceptor. The mechanism of the cell membrane is shown in Figure 3 [11].