Specificity of Training Effects on Aerobic Working Capacity and the Cardiovascular System
Atko Viru in Adaptation in Sports Training, 2017
Training effects on the mitochondria enable the use of oxidative phosphorylation for Adenosine Triphosphate (ATP) resynthesis during performance of more and more intensive exercises. The so-called anaerobic threshold is very likely a qualitative measure of the highest exercise intensity performed on the basis of oxidative phosphorylation without an extended use of anaerobic energy mechanisms. Since the maximal oxygen uptake is obtained in exercise level, causing a pronounced lactate accumulation, exercise intensity at VO 2 max does not indicate maximal performance on the basis of aerobic resynthesis of ATP. An integral index of the aerobic capacity of the organism is maximal oxygen uptake. Moreover, fundamental studies have established that VO 2 max is mainly set by cardiovascular determinants. Both strength and sprint training are also ineffective in increasing the functional capacity of the cardiovascular system. Olympic rowing team showed that a mean anaerobic threshold of 83% VO 2 max attests to the high aerobic capacity of oarsmen.
How Cells Obtain Energy from Food
Bruce Alberts, Dennis Bray, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, Peter Walter in Essential Cell Biolog, 2013
This chapter traces the major steps in the breakdown of sugars and shows how ATP, NADH, and other activated carriers are produced along the way. It concentrates on the breakdown of glucose because it generates most of the energy produced in the majority of animal cells. The chapter explains how cells use many of the molecules generated from the breakdown of sugars and fats as starting points to make other organic molecules. It examines how cells regulate their metabolism and how they store food molecules for their future metabolic needs. After digestion, the small organic molecules derived from food enter the cytosol of a cell, where their gradual oxidative breakdown begins. For most animal and plant cells, glycolysis is only a prelude to the third and final stage of the breakdown of food molecules, in which large amounts of ATP are generated in mitochondria by oxidative phosphorylation, a process that requires the consumption of oxygen.
The Phosphorus Enigma: An Overview
Enrique Maciá-Barber in The Chemical Evolution of Phosphorus, 2019
Living cells consist of a large variety of different biopolymers, namely, proteins, sugars, lipids, ribonucleic acids, and deoxyribonucleic acids. In fact, phosphorus compounds profusely appear in living systems where they perform many fundamental biochemical functions. Phosphorus, mainly in the form of phosphate derivatives, is a universal constituent of cells protoplasm and is required for growth, health, and reproduction in all forms of animals, plants, and bacteria. Adenosine triphosphate is the best-known conveyer of chemical energy in most metabolic routes, and this molecule also acts as an inorganic phosphate carrier in many important enzymatic reactions. Quite remarkably, the fact that most phosphorus on earth’s surface is in the form of phosphate leads to an important problem in prebiotic chemistry arising from the difficulty of the spontaneous phosphorylation of organic compounds by minerals likely present on the early earth’s crust.
Phosphorylation and protein–protein interactions in PXR-mediated CYP3A repression
Published in Expert Opinion on Drug Metabolism & Toxicology, 2009
Satyanarayana R Pondugula, Hanqing Dong, Taosheng Chen
Background: The expression of drug-metabolizing enzymes CYPs is controlled by pregnane X receptor (PXR), and, therefore, understanding how PXR modulates CYP expression is important to minimize adverse drug interactions, one type of preventable adverse drug reaction. Objective: We review the mechanisms of PXR-mediated repression of CYP expression. Methods: We discuss the clinical implications of CYP repression and the role of signal cross-talks, including protein–protein interactions and phosphorylation of PXR and coregulators, in inhibiting PXR and repressing CYP expression. Results/conclusion: Kinases such as cyclin-dependent kinase 2, protein kinase A, PKC and 70 kDa form of ribosomal protein S6 kinase repress CYP expression by phosphorylating and inhibiting PXR. Growth factor signaling represses CYP expression by phosphorylating and inhibiting forkhead in rhabdomyosarcoma, a co-activator of PXR. During inflammation, NF-κB represses both PXR and CYP expression through protein–protein interactions with the PXR pathway.
Regulation of muscle glycogen synthase phosphorylation and kinetic properties by insulin, exercise, adrenaline and role in insulin resistance
Published in Archives Of Physiology And Biochemistry, 2009
In mammals, excess carbohydrate is stored as glycogen and glycogen synthase is the enzyme that incorporates glucose units into the glycogen particle. Glycogen synthase activity is regulated by phosphorylation and allosterically activated by glucose 6-phosphate. Phosphorylation of nine serines by different kinases regulates glycogen synthase affinity for glucose 6-phosphate and its substrate UDP-glucose. Glucose 6-phosphate increases both enzyme activity and substrate affinity. Insulin and exercise increase glycogen synthase affinity for glucose 6-phosphate and activity whereas high glycogen content and adrenaline decrease affinity for glucose 6-phosphate and activity. However, insulin, exercise and adrenaline also regulate intracellular concentration of glucose 6-phosphate which will influence in vivo glycogen synthase activity. Importantly, type 2 diabetes is associated with reduced insulin-stimulated glycogen synthase activation. The nine phosphorylation sites theoretically allow 512 combinations of phosphorylation configurations of glycogen synthase with different kinetic properties. However, due to hierarchal phosphorylation, the number of configurations in vivo is most likely much lower. Unfortunately, many studies only report data on glycogen synthase activity measured with high concentration of UDP-glucose which holds back information about changes in substrate affinity. In this paper we discuss the physiological regulation of glycogen synthase phosphorylation and how the phosphorylation pattern regulates glycogen synthase kinetic properties.
Dissecting phosphorylation networks: lessons learned from yeast
Published in Expert Review of Proteomics, 2011
Janine Mok, Xiaowei Zhu, Michael Snyder
Protein phosphorylation continues to be regarded as one of the most important post-translational modifications found in eukaryotes and has been implicated in key roles in the development of a number of human diseases. In order to elucidate roles for the 518 human kinases, phosphorylation has routinely been studied using the budding yeast Saccharomyces cerevisiae as a model system. In recent years, a number of technologies have emerged to globally map phosphorylation in yeast. In this article, we review these technologies and discuss how these phosphorylation mapping efforts have shed light on our understanding of kinase signaling pathways and eukaryotic proteomic networks in general.
Related Knowledge Centers
- Mitochondria
- Oxidative Phosphorylation
- Metabolism
- Biochemical Phenomena
- Adp
- Atp
- Organic Chemistry Phenomena