ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
(from Greek, metabole: change) Metabolism (or a METABOLIC process) is the term given to all of the chemical changes that take place inside a living organism (animal or plant). It can be broken into two opposed components: CATABOLISM (from Greek, kata: down, ballein: to throw) and ANABOLISM (from Greek, ana: up, and ballein). Catabolism (or a catabolic process) is the name given to the process of breaking down molecules (see MOLECULE) into simpler units; it releases ENERGY. Anabolism (or an anabolic process) is a process of building more complex molecules from simpler units; it consumes energy. The term METABOLITE rcfers to a chemical that is the product of metabolism: a CATABOLITE is the product of catabolism, an anabolite the product of anabolism. Very often the more general term metabolite is used when more strictly catabolite would be correct. Note that the study of metabolism is central to an understanding of biology, being a central property of living things.
Cell Biology
C.S. Sureka, C. Armpilia in Radiation Biology for Medical Physicists, 2017
Metabolism is generally divided into two basic processes. They are (1) catabolism and (2) anabolism (Figure 1.6). Catabolism (destructive metabolism) is the process of breaking up large molecules (mostly carbohydrates and fats) into more simple molecules and produces energy by the way of cellular respiration (respiration is the process of oxidizing food molecules, like glucose, to carbon dioxide and water) and heat. This energy is used as fuel for anabolism, heats the body, and enables the muscles to contract and the body to move. It also produces waste products, such as CO2 etc., which is removed from the body through the skin, kidneys, lungs, and intestines. Anabolism (constructive metabolism) is the process of building and storing large biomolecules (proteins and nucleic acids) from small molecules (amino acids and nucleotides) using the energy generated from catabolism. Hence, it supports the growth of new cells, the maintenance of body tissues, and the storage of energy for future use. Anabolic and catabolic reactions take place simultaneously in cells throughout the body so that at any given moment, some biomolecules are being synthesized while others are being broken down. The energy released from or stored in the chemical bonds of biomolecules during metabolism is commonly measured in kilocalories (kcal).
Nutritional Requirements in Extreme Sports
Datta Sourya, Debasis Bagchi in Extreme and Rare Sports, 2019
Metabolism is the summation of competing pathways of anabolism—the synthesis of energy-storing complex molecules—and catabolism—the breakdown of complex molecules yielding energy. Though different tissues have preferred fuel sources to meet their specific functions, the metabolic state of any tissue is determined by the predominant pathway at any given time. For a much more detailed explanation of metabolism of various tissues, the reader is referred to Chapter 30 of Berg, Tymoczko, and Stryer (2002). It is also important to mention that all tissues do not need to be in the same metabolic state. In fact, the metabolic state of a tissue will vary based on function and state of the whole body. In this way, the body can compartmentalize systems and distribute energy based on demand in order to adapt and overcome a variety of stressors.
How metabolism and metabolites shape immunity during disease
Published in International Reviews of Immunology, 2022
Himanshu Kumar
Cellular metabolism is a complex biological process governed by numerous biochemical reactions that maintain various cellular processes essential for cell survival and continuity of life. It is not only important for the maintenance of host physiology, but also plays a crucial role in shaping the host’s defense system. The dynamicity of various immune components, immune responses and immune homeostasis during steady state or infection depends on the metabolic state of immune cells. Recently, it has been shown that various metabolite and metabolic enzymes play a pivotal role in the development of host immunity. This issue of International Reviews of Immunology focuses on the amino acid, sugar and lipid metabolisms and metabolic enzymes involved in host immunity during microbial infection and in different noninfectious defenses such as cancer, metabolic diseases and autoimmune diseases (Figure 1).
α-Hederin inhibits the growth of lung cancer A549 cells in vitro and in vivo by decreasing SIRT6 dependent glycolysis
Published in Pharmaceutical Biology, 2021
Cong Fang, Yahui Liu, Lanying Chen, Yingying Luo, Yaru Cui, Ni Zhang, Peng Liu, Mengjing Zhou, Yongyan Xie
Reprogramming energy metabolism is a hallmark of cancer. Energy metabolism is the process in which energy is generated from nutrients, released, stored, and consumed by organisms or living cells. Energy metabolism is divided into glucose metabolism, protein metabolism, and fat metabolism. Under normal conditions, cells generate energy primarily via aerobic respiration. When the oxygen content is insufficient, cells perform glycolysis to generate energy. This process is called anaerobic respiration. Unlike normal cells, tumour cells generate energy primarily via glycolysis, even under aerobic conditions, a phenomenon known as the Warburg effect. Glycolytic capacity is characterized by rapid productivity and low efficiency. The rapid proliferation of tumour cells requires rapid energy consumption. Meanwhile, the lactic acid generated by glycolysis creates an acidic environment for tumour cells, which is conducive to their growth and leads to their rapid proliferation (Zhao et al. 2014; Potter et al. 2016). Sirtuin 6 (SIRT6) protein is a chromatin binding factor that was initially described as an inhibitor of gene instability (Mostoslavsky et al. 2006). During energy metabolism, SIRT6 regulates the fat and glucose metabolism, which is a key regulator of energy stress and is closely related to the process of tumour growth (Sebastián and Mostoslavsky 2015). With the metabolic profile used for energy production is elucidated, regulating tumour metabolism is a new therapeutic strategy to inhibit tumour growth (Zhang and Yang 2013).
Subcutaneous catabolism of peptide therapeutics: bioanalytical approaches and ADME considerations
Published in Xenobiotica, 2022
Simone Esposito, Laura Orsatti, Vincenzo Pucci
The most relevant biotransformation occurring at the SC injection site is the cleavage of peptide bonds by means of proteases or peptidases, which generates smaller peptides or amino acids. This type of biotransformation is referred to as catabolism, in contrast to the term metabolism used for biotransformation mainly observed in small molecules. Proteolytic enzymes are broadly divided into two categories: exopeptidases, which catalyse the cleavage at the N-terminal or C-terminal removing a single amino acid, and endopeptidases, which cleave peptide bonds within the sequence (López-Otín and Bond 2008). Exopeptidases are intuitively divided into aminopeptidases and carboxypeptidases, while endopeptidases are traditionally classified on the basis of their catalytic site as cysteine peptidases (e.g. dipeptidyl peptidase IV), aspartic peptidases (e.g. pepsin), serine peptidases (e.g. cathepsin B), and metallopeptidases (e.g. matrix metalloprotease 2 and 9) (de Veer et al. 2014a).