A Complementary Radiopharmaceutical and Mathematical Model for Quantitating Hepatic-Binding Protein Receptors
William C. Eckelman, Lelio G. Colombetti in Receptor-Binding Radiotracers, 2017
Recent research in molecular biology has implicated cell surface glycoproteins, with their highly variable arrangements of sugar moieties, as the identifying markers that allow cells to uniquely distinguish individual chemical structures. The macromolecules which exhibit the property of recognition and binding of specific carbohydrate sequences are referred to as lectins.1 Carbohydrate-mediated recognition reactions allow more combinations of chemically unique receptor sites than are possible with polypeptides. While there are 20 common structural units in the latter case and only nine sugars, glycosidic bonds allow extensive structural branching that is unimportant in peptide bonding. The number of conceivable combinations and permutations of polypeptide structures is thus small compared to that for the highly branched oligosaccharides for which this number approaches 1024.2
Role of Tumor Cell Membrane in Hyperthermia
Leopold J. Anghileri, Jacques Robert in Hyperthermia In Cancer Treatment, 2019
Glycoproteins and glycolipids are components in the plasma membrane of all mammalian cells. Glycoproteins usually contain multiple sugar chains with different structures. The identification of the carbohydrate moieties of a great number of glycoproteins and glycolipids has been accomplished during the last two decades.97,98 All sugar molecules in a glycoprotein are attached to the polypeptide backbone as side chains of oligosaccharides or polysaccharides that are formed by O-glycosidic bonds between carbon-1 (the anomeric carbon) of one monosaccharide and any of three or more ring carbons of another monosaccharide. Alpha- or beta-glycosidic linkages can be formed by the anomeric carbon; in each case the oxygen atom is below or above the plane of the sugar ring, respectively. The carbohydrate-peptide linkage takes place through the terminal reducing groups of these oligo- or polysaccharides (Figure 6). Pronase digestion of glycoproteins and analysis of the isolated glycopeptides has been the method used to isolate carbohydrate chains for structural analysis.99
Chemopreventive Agents
David E. Thurston, Ilona Pysz in Chemistry and Pharmacology of Anticancer Drugs, 2021
Quercetin (Figure 12.8) is widely distributed in the plant kingdom and is mainly found in the outer parts and leaves in the form of aglycones and glycosides. In the latter, one or more sugar groups are bound to the phenolic groups via glycosidic bonds. Its name is associated with the Latin “quercetum” (meaning oak forest) and the genus Quercus to which oak trees belong. In its pure form quercetin is a yellow crystalline powder (Figure 12.9A) that is virtually insoluble in water but will dissolve in aqueous alkaline solutions. It has a reputation for providing health benefits, including as a chemopreventive agent, and many brands of supplements are available in health food stores worldwide (Figure 12.9B).
Bacteriophage endolysins as a potential weapon to combat Clostridioides difficile infection
Published in Gut Microbes, 2020
Shakhinur Islam Mondal, Lorraine A. Draper, R Paul Ross, Colin Hill
Cell wall hydrolases (CWHs) are classified based on their origin as endolysins, exolysins and/or autolysins.95,96 Some of the C. difficile phage/prophages contain putative CWH sequences that may have potent lytic activity as endolysins (Table 2). The major catalytic domains present in C. difficile phage/prophage CWHs are NlpC/P60 and glucosaminidase. The NlpC/P60 domain is described as a superfamily and has a diverse range of catalytic activity including cleaving N-acetylmuramate-L-alanine linkages and the 4–3 linkage between D-Glu and m-DAP residues.97–99 The glucosaminadases hydrolyze the glycosidic bond of the sugar backbone. The putative N-acetylglucosaminidases (EC.3.2.1.96) that are present in C. difficile phages/prophages were also present in the prophage LambdaSa2 of Streptococcus agalactiae and exhibit β-D-N-acetylglucosaminidase activity.100
Targeting glyco-immune checkpoints for cancer therapy
Published in Expert Opinion on Biological Therapy, 2021
Glycans are carbohydrate-containing molecules which play an important role in several biological functions, including cell adhesion, metabolism, and immune surveillance [5,6]. Glycans can be found in the extracellular matrix as free chains of glycosaminoglycans, at the cell surface in the form of glycoproteins and glycolipids, and as intracellular glycosylated proteins [6–8]. Glycosylation is an enzymatic process that generates glycosidic bonds. This process takes place predominantly in the endoplasmic reticulum and in the Golgi apparatus and it involves the coordinated action of several glycosyltransferases and glycosidases [6,8]. Given the importance of glycans, it is not surprising that glycosylation is controlled at several levels, including gene expression and localization of glycosyltransferases and glycosidases, and substrate availability [6,8].
Recent treatment modalities for cardiovascular diseases with a focus on stem cells, aptamers, exosomes and nanomedicine
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Rahul Mittal, Vasanti M. Jhaveri, Hannah S. McMurry, Sae-In Samantha Kay, Kyle J. Sutherland, Lin Nicole, Jeenu Mittal, Rahul Dev Jayant
A polysaccharide-based nanosystem is a popular avenue for targeting certain cardiovascular pathologies such as atherothrombotic disease. Polysaccharides are long-chain carbohydrate molecules that are made up of identical monosaccharide units. These individual units are held together by glycosidic bonds. Polysaccharides not only have great structural diversity but also play a role in a variety of cellular functions including cell signalling and adhesion [57]. Atherothrombotic pathology is highly associated with polysaccharide recognition, which allows for both targeted and inhibitory therapy [58]. The well-known polysaccharide-based nanosystems used to combat atherosclerotic-related pathological disease include chitosan and dextran-coated nanoparticles. Chitosan is a linear polysaccharide that is protonated in acidic to neutral solutions rendering it as a hydrophilic cationic polyelectrolyte [59]. Due to electrostatic interactions, chitosan has been noted to strongly interact with fibrin, a negatively charged fibrous protein [60]. Chung et al. conducted an in vitro study to examine whether chitosan-coated nanoparticles could enhance clot penetration by reducing time needed for thrombolysis using tissue-plasminogen activator (t-PA) [61]. Results showed that t-PA-loaded nanoparticles had a significantly lesser t-PA-related thrombolysis time than t-PA administered alone in solution. Furthermore, results showed that t-PA-loaded nanoparticles also greatly helped with clot permeation.
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