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Macronutrients
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
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).
Antiviral Agents and Rational Drug Design
Published in Nathan Keighley, Miraculous Medicines and the Chemistry of Drug Design, 2020
The (−) single-stranded RNA of influenza is contained within the capsid, which itself is enveloped in an outer membrane constructed from that of the host cell and contains two viral glycoproteins: neuraminidase (NA) and hemagglutinin (HA); so called because it can bind to red blood cells. The function of these two glycoproteins is to facilitate the infection process. NA helps the virus to traverse the mucus layers of the respiratory tract by catalysing degradation of the mucus layer, thus enabling the virus to reach the surface epithelial cells. Once there, adsorption of the virus can occur, whereby the virus binds to the host cell receptors that are recognised by HA, which binds to them rather than catalysing their degradation. The virion is now adsorbed; this process is known as receptor-mediated endocytosis. The pH then decreases inside the endosome, which is the membrane-bound compartment inside the host cell that contains the virion, causing HA to drastically change its conformation, where the hydrophobic ends of the protein fold outwards; extending towards the endosomal membrane and fusion occurs on contact, enabling the RNA capsid to be released into the cytoplasm of the host cell. Disintegration of the capsid releases the RNA and the viral enzyme RNA polymerase; both of which invade the nucleus.
Eosinophil–Endothelial Interactions and Transendothelial Migration
Published in Bruce S. Bochner, Adhesion Molecules in Allergic Disease, 2020
Motohiro Ebisawa, Bruce S. Bochner, Robert P. Schleimer
Several cell surface glycoproteins on endothelial cells are able to mediate adhesion. These molecules are grouped on the basis of shared structural characteristics. On endothelial cells, those belonging to the immunoglobulin gene superfamily, which consists of more than a dozen structures, include ICAM-1, ICAM-2, VCAM-1, and platelet-endothelial cell adhesion molecule-1 (PECAM-1) (Table 1) (8). Another family of adhesion molecules, of which there are three known members, is the selectin gene superfamily (9). Two members of this family, E-selectin (originally endothelial-leukocyte adhesion molecule-1 [ELAM-1]) and P-selectin (formerly GMP-140) can be expressed on endothelial cells upon stimulation (Table 1). Endothelial cells constitutively express ICAM-1, ICAM-2, and PECAM-1 on their surface. In contrast to these molecules, VCAM-1 and E-selectin are not expressed on resting endothelial cells, and various cytokines are known to induce their expression in addition to ICAM-1 (Table 1) (10). P-selectin is not expressed on the resting endothelium, and is rapidly expressed after stimulation with histamine or thrombin (11). E-selectin and P-selectin have lectin domains to bind carbohydrate structures, such as those containing sialylated Lewis X antigen (sLex) (11).
Central retinal artery occlusion and subsequent amaurosis fugax in the contralateral eye associated with the G20210A prothrombin gene (F2) variant: a case report
Published in Ophthalmic Genetics, 2022
María Camila Sierra-Cote, Juliana Muñoz-Ortiz, Juan Sebastián Botero-Meneses, Carolina Saldarriaga-Santos, Natalia Camacho, William Rojas-Carabali, Alejandra de-la-Torre
Regarding the genetic component, one of the most common variants in the prothrombin gene (F2) is the G20210A. Prothrombin is a glycoprotein and precursor form of Factor II (thrombin), and it is essential for the final phase of clotting (5). It is encoded by the F2 gene located in the short arm of chromosome 11 (11p11.2). Variants in this gene, including polymorphisms and variants, may lead to thrombophilic disorders in many patients (6,7). Although the G20210A is an established risk factor for venous thrombosis, and it is debatable that this variant is a risk factor for arterial thromboembolism, some cases have been linked to myocardial infarction and cerebral arterial disease (8). In the case of ocular vessel occlusions, studies are scarce (9–12). This study aims to report the fourth case described in the literature of CRAO associated with prothrombin G20210A pathogenic variant and the first case with bilateral ocular findings (9–11), emphasizing the usefulness of OCT-A in reaching the diagnosis and establishing the specific and timely therapeutic measures.
Signal peptide peptidase: a potential therapeutic target for parasitic and viral infections
Published in Expert Opinion on Therapeutic Targets, 2022
Christopher Schwake, Michael Hyon, Athar H. Chishti
SPP is essential for eukaryotic homeostasis and has been proven to be a crucial target of disruption in parasitic disease. Owing to its essentiality, we sought to examine if human viral infections take advantage of host SPP during their replicative life cycle. A growing body of evidence is beginning to unveil the importance of SPP-mediated processing of host viral proteins. Many viruses produce a large polyprotein that is catalytically cleaved to generate mature viral products and in some viral pathogens the host SPP is utilized to complete this essential step. SPP was also found to play a functional role in viral processing and propagation mainly through interaction with surface glycoproteins. Entry of enveloped viruses is mediated through binding of these glycoproteins to host cell receptors allowing for membrane fusion. In order to function, these glycoproteins must be activated by host cell proteases. Inhibition of host SPP prevents viral fusion and entry events in several human viral pathogens. As we will outline below, viruses utilize SPP for both cell entry and SPP-mediated regulation of immune responses. Therefore, SPP may prove to be a critical host component for ensuring optimal infection in many important human viral pathogens.
Production of bioactive recombinant ovine cysteine-rich secretory protein 1 in Escherichia coli
Published in Systems Biology in Reproductive Medicine, 2021
Kalpana Jorasia, Rajani Kr. Paul, N. S. Rathore, Pyare Lal, R. Singh, Meenaxi Sareen
Cysteine-rich secretory proteins (CRISPs) are a subgroup of CRISP, antigen 5, pathogenesis-related protein 1 (CAP) super-family, characterized by the presence of N-terminal CAP domain (21 kDa) that contains six conserved cysteine residues, and the C-terminal CRISP domain (6 kDa) that contains 10 conserved cysteine residues (Gibbs et al. 2008). These are acidic glycoproteins of epididymal origin and are reported to bind to the sperm surface. In vitro studies have revealed that CRISP-1 prevents protein tyrosine phosphorylation and acrosome reaction reversibly, and its disassociation from the sperm surface was required for inducing capacitation (Roberts et al. 2003). However, a part of the protein remains on spermatozoa after capacitation, localized in the equatorial segment of sperm, and is involved in gamete fusion (Cohen et al. 2000; Busso et al. 2007). The observations of several studies have suggested that CRISP-1 is a multi-functional protein playing different roles during fertilization through various associations with and localization on spermatozoa (Cohen et al. 2013).