Hydrolysis is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
The isoelectric point (pI, pH(I), IEP), is the pH at which a molecule carries no net electrical charge or is electrically neutral in the statistical mean. The standard nomenclature to represent the isoelectric point is pH(I). However, pI is also used. For brevity, this article uses pI. The net charge on the molecule is affected by pH of its surrounding environment and can become more positively or negatively charged due to the gain or loss, respectively, of protons (H+).
Anabolism is the set of metabolic pathways that construct macromolecules like DNA or RNA from smaller units. These reactions require energy, known also as an endergonic process. Anabolism is the building-up aspect of metabolism, whereas catabolism is the breaking-down aspect. Anabolism is usually synonymous with biosynthesis.
Sialic acids are a class of alpha-keto acid sugars with a nine-carbon backbone. The term "sialic acid" was first introduced by Swedish biochemist Gunnar Blix in 1952. The most common member of this group is N-acetylneuraminic acid found in animals and some prokaryotes.
Proteoglycans are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s). The point of attachment is a serine (Ser) residue to which the glycosaminoglycan is joined through a tetrasaccharide bridge. The Ser residue is generally in the sequence -Ser-Gly-X-Gly-, although not every protein with this sequence has an attached glycosaminoglycan. The chains are long, linear carbohydrate polymers that are negatively charged under physiological conditions due to the occurrence of sulfate and uronic acid groups. Proteoglycans occur in connective tissue.
Ion chromatography is a form of chromatography that separates ions and ionizable polar molecules based on their affinity to the ion exchanger. It works on almost any kind of charged molecule—including small inorganic anions, large proteins, small nucleotides, and amino acids. However, ion chromatography must be done in conditions that are one pH unit away from the isoelectric point of a protein.
In mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that uses a laser energy-absorbing matrix to create ions from large molecules with minimal fragmentation. It has been applied to the analysis of biomolecules and various organic molecules, which tend to be fragile and fragment when ionized by more conventional ionization methods. It is similar in character to electrospray ionization (ESI) in that both techniques are relatively soft ways of obtaining ions of large molecules in the gas phase, though MALDI typically produces far fewer multi-charged ions.
A glycophorin is a sialoglycoprotein of the membrane of a red blood cell. It is a membrane-spanning protein and carries sugar molecules. It is heavily glycosylated (60%). Glycophorins are rich in sialic acid, which gives the red blood cells a very hydrophilic-charged coat. This enables them to circulate without adhering to other cells or vessel walls.
Cytosol alanyl aminopeptidase is an enzyme.
Sialyltransferases are enzymes that transfer sialic acid to nascent oligosaccharide. Each sialyltransferase is specific for a particular sugar substrate. Sialyltransferases add sialic acid to the terminal portions of the sialylated glycolipids (gangliosides) or to the N- or O-linked sugar chains of glycoproteins.
N-Acetylmannosamine is a hexosamine monosaccharide. It is a neutral, stable naturally occurring compound. N-Acetylmannosamine is also known as N-Acetyl-D-mannosamine monohydrate,, N-Acetyl-D-mannosamine which can be abbreviated to ManNAc or, less commonly, NAM). ManNAc is the first committed biological precursor of N-acetylneuraminic acid. Sialic acids are the negatively charged, terminal monosaccharides of carbohydrate chains that are attached to glycoproteins and glycolipids (glycans).
In renal physiology, ultrafiltration occurs at the barrier between the blood and the filtrate in the glomerular capsule in the kidneys. As in nonbiological examples of ultrafiltration, pressure and concentration gradients lead to a separation through a semipermeable membrane. The Bowman's capsule contains a dense capillary network called the glomerulus. Blood flows into these capillaries through the afferent arterioles and leaves through the efferent arterioles.
Siglecs(Sialic acid-binding immunoglobulin-type lectins) are cell surface proteins that bind sialic acid. They are found primarily on the surface of immune cells and are a subset of the I-type lectins. There are 14 different mammalian Siglecs, providing an array of different functions based on cell surface receptor-ligand interactions.
Sialoadhesin is a cell adhesion molecule found on the surface of macrophages. It is found in especially high amounts on macrophages of the spleen, liver, lymph node, bone marrow, colon, and lungs. Also, in patients with rheumatoid arthritis, the protein has been found in great amounts on macrophages of the affected tissues. It is defined as an I-type lectin, since it contains 17 immunoglobulin (Ig) domains, and thus also belongs to the immunoglobulin superfamily (IgSF). Sialoadhesin binds to certain molecules called sialic acids. During this binding process a salt bridge (protein) is formed between a highly conserved arginine residue and the carboxylate group of the sialic acid. Since sialoadhesin binds sialic acids with its N-terminal IgV-domain, it is also a member of the SIGLEC family. Alternate names for sialoadhesin include siglec-1 and CD169.
Leukosialin also known as sialophorin or CD43 is a transmembrane cell surface protein that in humans is encoded by the SPN (sialophorin) gene.
Sialic acid-binding Ig-like lectin 7 is a protein that in humans is encoded by the SIGLEC7 gene. SIGLEC7 has also been designated as CD328.
Polysialic acid is an unusual posttranslational modification that occurs on neural cell adhesion molecules (NCAM). Polysialic acid is considerably anionic. This strong negative charge gives this modification the ability to change the protein's surface charge and binding ability. In the synapse, polysialation of NCAM prevents its ability to bind to NCAMs on the adjacent membrane.
Viral neuraminidase is a type of neuraminidase found on the surface of influenza viruses that enables the virus to be released from the host cell. Neuraminidases are enzymes that cleave sialic acid groups from glycoproteins. Viral neuraminidase was discovered by Alfred Gottschalk at the Walter and Eliza Hall Institute in 1957. Neuraminidase inhibitors are antiviral agents that inhibit influenza viral neuraminidase activity and are of major importance in the control of influenza.
Feline coronavirus (FCoV) is a positive-stranded RNA virus that infects cats worldwide. It is a coronavirus of the species Alphacoronavirus 1, which includes canine coronavirus (CCoV) and porcine transmissible gastroenteritis coronavirus (TGEV). FCoV has two different forms: feline enteric coronavirus (FECV), which infects the intestines, and feline infectious peritonitis virus (FIPV), which causes the disease feline infectious peritonitis (FIP).
The cell membrane is a biological membrane that separates and protects the interior of a cell from the outside environment. The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of a cell, being selectively permeable to ions and organic molecules. In addition, cell membranes are involved in a variety of cellular processes such as cell adhesion, ion conductivity, and cell signalling and serve as the attachment surface for several extracellular structures, including the cell wall and the carbohydrate layer called the glycocalyx, as well as the intracellular network of protein fibers called the cytoskeleton. In the field of synthetic biology, cell membranes can be artificially reassembled.
