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Energy Provision, Fuel Use and Regulation of Skeletal Muscle Metabolism During The Exercise Intensity/Duration Continuum
Published in Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse, The Routledge Handbook on Biochemistry of Exercise, 2020
At the same time, cellular Ca2+ (and to some extent epinephrine [EPI] from outside the cell) activates phosphorylase kinase to move glycogen phosphorylase from its less active “b” form to the more active “a” form in what is called covalent regulation. Increases in ADP and adenosine monophosphate (AMP) (Figure 2.4) also activate phosphorylase a directly (allosteric regulation) to degrade glycogen and combine with Pi to produce glucose 1-phosphate, glucose 6-phosphate (G-6-P), and fructose 6-phosphate (F-6-P) in the glycolytic pathway (19, 70). Phosphorylase is considered a “non-equilibrium enzyme,” as it is controlled by external factors and not just substrates and products. This impressive combination of covalent and allosteric regulation explains how the flux through phosphorylase can increase from very low rates at rest to very high rates during intense exercise in only a few msec! The increases in allosteric regulators ADP, AMP, and Pi (which are by-products of ATP breakdown, Figure 2.4) and the accumulating substrate F-6-P activate the regulatory enzyme phosphofructokinase and flux through the reactions of the glycolytic pathway, which continues with a net production of 3 ATP and lactate formation.
Maturation of Brain ATP Metabolism
Published in Richard A. Jonas, Jane W. Newburger, Joseph J. Volpe, John W. Kirklin, Brain Injury and Pediatric Cardiac Surgery, 2019
Between 12 and 17 days of age, rat cerebral cortical tissue develops the capacity to increase rates of aerobic glycolysis 60% to 100% in response to rapid increases in ATP use. Metabolic stimulation, designed to model in vivo physiological and pathological conditions, includes electrical pulses (Figure 3-8A), increased extracellular KCl (Figure 3-8C), hyperthermia (Figure 3-C). In contrast to the slower development of glycolytic and most tricarboxylic acid cycle enzymes described in the previous section, the brief maturational time course also is seen in the increasing pyruvate and lactate dehydrogenase activities in rat cerebral cortex.41,42 These regulatory enzymes couple glycolysis with pathways of aerobic metabolism. The maximal respiratory capacity and the fraction of respiration coupled to ATP synthesis in rat cerebral cortical tissue also increase markedly in this brief developmental period.68
Phosphatidate Phosphohydrolase Activity in Adipose Tissue
Published in David N. Brindley, John R. Sabine, Phosphatidate Phosphohydrolase, 2017
It is clear that the Mg2+ -dependent phosphohydrolase in white adipose tissue shows complex regulatory properties both short term and long term. In most instances these properties can be correlated with and integrated into the overall picture of the regulation of adipose tissue metabolism. It is probably simplistic to assign a dominant role to any regulatory enzyme in the overall control of any metabolic process. Rather, it is better to think in terms of the close-knit interplay between several regulatory enzymes. At the present time this must be considered to be the situation regarding the role of the phosphohydrolase partly because our knowledge is still incomplete and partly because it is clear that other enzymes in the triacylglycerol synthesis pathway are also regulated.
Altered VDAC-HK association and apoptosis in mouse peripheral blood lymphocytes exposed to diabetic condition: an in vitro and in vivo study
Published in Archives of Physiology and Biochemistry, 2023
Melinda Nongbet Sohlang, Suktilang Majaw
The regulatory enzyme(s) of glycolysis and its alternate glucose utilisation pathway, the pentose phosphate pathway, plays an important role in the metabolic survival of the cell (Porter and Janicke 1999, Fiorillo et al. 2006, Jiang et al. 2014). A previous study has suggested that suppression of glycolysis can lead to cell death (Otsuki et al. 2005), this may be due to decreased HK activity and/or expression under high glucose (Zhang et al. 2019) and PA condition (Broniarek et al. 2016). Treatment of PBL to high Glc/PA for 72 h significantly reduced the HK and G6PDH activity when compared to their respective control. Diabetes also reduces the activities of HK and G6PDH (p < .001) in PBL compared to the control (Table 1). The reduced HK enzyme activity in PBL exposed to high Glc/PA (da-Silva et al. 2004, Park et al. 2015) including those isolated from diabetic mice (Unakal and Newman 2014) has been reported elsewhere. Further, the reduction in G6PDH activity in the treated condition may have led to G6P non-utilization and accumulation contributing to reduced HK activity (Zhang et al.2019, Fraenkel 1968).
An overview of carbonic anhydrases and membrane channels of synoviocytes in inflamed joints
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2019
Currently, experimental evidence for the involvement of CAs and FLS membrane channels in RA is limited. The physiological and pathological roles of ion channels and transporters in dynamic FLS migration have not yet been studied in detail. Here, we have summarised the studies on membrane channels and regulatory enzymes of RA-FLS with an aim to understand their migrated state. However, many questions regarding RA-FLS still need to be clarified. What are the exact molecular mechanisms by which ion transporter affects the FLS migration apparatus? What are the exact components of synovial fluid that mediate the FLS dynamics? What are the components affecting the differential expression of CAs and membrane channels in FLS? What is the combined mechanism of CAs as regulatory enzymes? Several membrane channels and transporters show tissue-specific expression. Thus, unravelling the mechanisms by which ion channels and transporters are positioned in and modulate the migration of activated FLS will be a rewarding pursuit for the coming years. The motivation of channel physiologists is also needed to develop potential therapeutics to counter the critical pathophysiological involvement of FLS migration in joints in RA.
Biogenesis of silver nanoparticles using leaf extract of Indigofera hirsuta L. and their potential biomedical applications (3-in-1 system)
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Vasudeva Reddy Netala, Suman Bukke, Latha Domdi, S. Soneya, Sindhu G. Reddy, Murali Satyanarayana Bethu, Venkata Subbaiah Kotakdi, K. V. Saritha, Vijaya Tartte
The antimicrobial activity of the IH-AgNPs mainly depends on the size, shape and negative surface charge. The difference in inhibitory activity of the IH-AgNPs against different microbes could also due to the variations in membrane composition of bacteria and fungi. Ultra sized IH-AgNPs possess larger surface area to volume ratio which enhances the contact surface of IH-AgNPs to microorganism which in turn enhances the antimicrobial activity. The effective activity of the IH-AgNPs synthesized in this study might be due to their smaller size (5–10 nm) and high negative surface charge (−37.0 mV). The plausible mechanism behind the inhibitory activity of IH-AgNPs against different bacteria and fungi was also explained. IH-AgNPs caused the bacterial cell death by membrane disruption and bacterial DNA fragmentation [53,54]. IH-AgNPs bind with active site of regulatory enzymes that are important for bacterial cell division. As a result bacterial cell death occurs. Proteomic analysis revealed that IH-AgNPs can disrupt the cell membranes by altering the expression of membrane proteins which leads to leakage of intracellular ions and reducing sugars and eventually leads to death [55].