Macronutrients
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Conjugated proteins or Heteroproteins consist of a simple protein combined with a nonprotein component. The nonprotein component is called a prosthetic group (36, 47). A protein without its prosthetic group is called an apoprotein. A protein molecule combined with its prosthetic group forms a heteroprotein. Prosthetic groups play an important role in the function of proteins. Conjugated proteins are classified according to the nature of their prosthetic groups. They include glycoproteins, lipoproteins, metalloproteins, hemoproteins, phosphoproteins, and so on. Glycoproteins contain a carbohydrate component. Lipoproteins are proteins containing lipid molecules such as cholesterol which are divided into High-Density Lipoprotein (HDL) or ‘good’ cholesterol and Low-Density Lipoprotein (LDL) or ‘bad’ cholesterol. Metalloproteins contain metal ions (iron, calcium, copper, zinc, and molybdenum). Phosphoproteins contain phosphate groups, while hemoproteins or chromoproteins possess heme groups such as hemoglobin. Hemoglobin is the metalloprotein containing iron for the transport of oxygen in the red blood cells of all mammals (36, 47).
The Glutathione Redox State and Zinc Mobilization from Metallothionein and Other Proteins with Zinc–Sulfur Coordination Sites
Christopher A. Shaw in Glutathione in the Nervous System, 2018
The amount of zinc (2–3 g) and its daily requirement (2–7 mg, depending on its availability in the diet) in a 70-kg adult human are close to those of iron (4–5 g and about 10 mg, respectively). It is also true that whereas the functions of iron in oxidoreduction (cytochromes) and oxygen transport and storage (hemoglobin and myoglobin) are specific and well defined, zinc-dependent functions are much more widespread. Thus, zinc is an essential element of paramount importance for growth and development, metabolism, the immune response, gene expression, and neurotransmission, among others. Over the past 10 years, expanding progress in the recognition of zinc-dependent functions (Vallee and Falchuk 1993) and in the elucidation of the molecular structure of many different motifs of zinc sites in proteins (Vallee and Auld 1993) has stimulated interest in this element in almost all branches of the biomedical sciences. Virtually all roles of zinc so far are linked to function and structure of proteins. In fact, zinc-containing proteins form a much larger group than any of the other metalloproteins. More than 200 zinc enzymes have been recognized, in all seven of the classes defined by the commission for enzyme nomenclature of the International Union of Biochemistry and Molecular Biology (Vallee and Falchuk 1993), and an estimated 500 zinc finger genes of just one of the many classes exist in humans (Becker et al. 1995).
Metallothionein
Lars Friberg, Tord Kjellström, Carl-Gustaf Elinder, Gunnar F. Nordberg in Cadmium and Health: A Toxicological and Epidemiological Appraisal, 2019
In 1957, Margoshes and Vallee62 reported the isolation of a low molecular weight cadmium-binding protein from horse renal cortex. Subsequent work by Kägi and Vallee47,48 resulted in the purification of a metalloprotein, with a molecular size of about 10,000 daltons, which they named metallothionein because of its high content of metals (cadmium and zinc) and sulfur. Later studies have shown that the actual molecular weight is about 6,500,72 based on amino acid residues. This metalloprotein was shown to have many unique physicochemical properties (Table 1).
Ferroptosis, a new form of cell death defined after radiation exposure
Published in International Journal of Radiation Biology, 2022
Xiaohong Zhang, Xin Li, Chunyan Zheng, Chunzhi Yang, Rui Zhang, Ailian Wang, Jundong Feng, Xiaodan Hu, Shuquan Chang, Haiqian Zhang
Iron metabolism is a set of metalloprotein-associated chemical reactions that maintain homeostasis in iron acquisition, utilization, transportation, and storage (Wang and Pantopoulow 2011). Many researchers have demonstrated that iron is essential for ferroptosis. For instance, iron chelators (deferoxamine and 2,2-bipyridyl) block cells from undergoing ferroptosis (Dixon et al. 2012). An exogenous supplement of iron increases the sensitivity of cells to erastin (Wu et al. 2021). Excessive heme and non-heme iron can directly induce ferroptosis (Li et al. 2017). The effect of iron on ferroptosis attributes to its ability to enhance the lipid peroxidation (Willmore and Triggs 1991). Since iron affects of ferroptosis, iron metabolic proteins that regulate iron have attracted increasing attention in ferroptosis regulation.
Potential of Application of Iron Chelating Agents in Ophthalmic Diseases
Published in Seminars in Ophthalmology, 2021
Alireza Ghaffarieh, Joseph B. Ciolino
Understanding how iron metabolism and infectious agents interact might suggest new methods to control the disease. Investigations indicate that iron loading can exacerbate viral disease. Therefore, it is plausible that reducing cellular or body iron stores could influence disease pathogenesis, as seems to be the case for viral infection.4 Iron withdrawal is part of the natural innate immune response in infection. During inflammation and infection, a “hypoferremic response” is observed (anemia of inflammation).5 Replication of HIV-1, Herpes simplex, CMV, HBV, HCV, Epstein-Barr virus, Parvovirus B-19, Coxsackie-B, and Herpes Zoster can be influenced by iron.6,7 Hence, decreasing the availability of iron may inhibit viral replication. Almost a third of all viral proteins are metalloproteins, with some responsible for a wide variety of essential viral functions.4,8
Prospects for the introduction of targeted antioxidant drugs for the prevention and treatment of diseases related to free radical pathology
Published in Expert Opinion on Investigational Drugs, 2019
George J Kontoghiorghes, Christina N Kontoghiorghe
Iron and copper are essential for the production of FR in biological systems, whether in metalloenzymes, metalloproteins in mitochondria or as low molecular weight metal complexes. The transport, storage and utilisation of these metals are controlled by metabolic pathways involving specific proteins. Transferrin can mobilise and carry up to two molecules of iron in blood and is regarded as a powerful natural chelator and antioxidant [6]. Ferritin is found in all the cells and can store up to 4500 molecules of iron in polynuclear complex formation, which is normally not involved in redox reactions. Under certain conditions e.g. cellular damage, labile iron or copper is released which can catalyse FR reactions and cascades leading to a vicious circle of OST and damage (Figure 1) [7]. Free radicals and ROS are also formed from UV radiation, radioactivity, heat, chemical reactants and heavy metals.
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