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Mannose
Mannose is a sugar with the formula , which sometimes is abbreviated Man. It is one of the monomers of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, especially in the glycosylation of certain proteins. Several congenital disorders of glycosylation are associated with mutations in enzymes involved in mannose metabolism. Mannose is not an essential nutrient; it can be produced in the human body from glucose, or converted into glucose. Mannose provides 2–5 kcal/g. It is partially excreted in the urine. Etymology The root of both "mannose" and " mannitol" is manna, which the Bible describes as the food supplied to the Israelites during their journey in the region of Sinai. Several trees and shrubs can produce a substance called manna, such as the "manna tree" (''Fraxinus ornus'') from whose secretions mannitol was originally isolated. Structure Mannose commonly exists as two different-sized rings, the py ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mannose Metabolism
Mannose is a sugar with the formula , which sometimes is abbreviated Man. It is one of the monomers of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, especially in the glycosylation of certain proteins. Several Congenital disorder of glycosylation, congenital disorders of glycosylation are associated with mutations in enzymes involved in mannose metabolism. Mannose is not an essential nutrient; it can be produced in the human body from glucose, or converted into glucose. Mannose provides 2–5 kcal/g. It is partially excreted in the urine. Etymology The root of both "mannose" and "mannitol" is manna, which the Bible describes as the food supplied to the Israelites during their journey in the region of Sinai Peninsula, Sinai. Several trees and shrubs can produce a substance called manna, such as the "manna tree" (''Fraxinus ornus'') from whose secretions mannitol was originally isolated. Structure Mannose comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congenital Disorder Of Glycosylation
A congenital disorder of glycosylation (previously called carbohydrate-deficient glycoprotein syndrome) is one of several rare inborn errors of metabolism in which glycosylation of a variety of tissue proteins and/or lipids is deficient or defective. Congenital disorders of glycosylation are sometimes known as CDG syndromes. They often cause serious, sometimes fatal, malfunction of several different organ systems (especially the nervous system, muscles, and intestines) in affected infants. The most common sub-type is PMM2-CDG (formerly known as CDG-Ia) where the genetic defect leads to the loss of phosphomannomutase 2 ( PMM2), the enzyme responsible for the conversion of mannose-6-phosphate into mannose-1-phosphate. Presentation Clinical features depend on the molecular pathology of the particular CDG subtype. Common manifestations include |
Glucose
Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using energy from sunlight. It is used by plants to make cellulose, the most abundant carbohydrate in the world, for use in cell walls, and by all living Organism, organisms to make adenosine triphosphate (ATP), which is used by the cell as energy. In energy metabolism, glucose is the most important source of energy in all organisms. Glucose for metabolism is stored as a polymer, in plants mainly as amylose and amylopectin, and in animals as glycogen. Glucose circulates in the blood of animals as blood sugar. The naturally occurring form is -glucose, while its Stereoisomerism, stereoisomer L-glucose, -glucose is produced synthetically in comparatively small amounts and is less biologicall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldohexose
In chemistry, a hexose is a monosaccharide (simple sugar) with six carbon atoms. The chemical formula for all hexoses is , and their molecular weight is 180.156 g/mol. Hexoses exist in two forms, open-chain or cyclic, that easily convert into each other in aqueous solutions. The open-chain form of a hexose, which usually is favored in solutions, has the general structure , where ''n'' is 1, 2, 3, 4, 5. Namely, five of the carbons have one hydroxyl functional group () each, connected by a single bond, and one has an oxo group (), forming a carbonyl group (). The remaining bonds of the carbon atoms are satisfied by seven hydrogen atoms. The carbons are commonly numbered 1 to 6 starting at the end closest to the carbonyl. Hexoses are extremely important in biochemistry, both as isolated molecules (such as glucose and fructose) and as building blocks of other compounds such as starch, cellulose, and glycosides. Hexoses can form dihexose (like sucrose) by a condensation reacti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycosylation
Glycosylation is the reaction in which a carbohydrate (or ' glycan'), i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule (a glycosyl acceptor) in order to form a glycoconjugate. In biology (but not always in chemistry), glycosylation usually refers to an enzyme-catalysed reaction, whereas glycation (also 'non-enzymatic glycation' and 'non-enzymatic glycosylation') may refer to a non-enzymatic reaction. Glycosylation is a form of co-translational and post-translational modification. Glycans serve a variety of structural and functional roles in membrane and secreted proteins. The majority of proteins synthesized in the rough endoplasmic reticulum undergo glycosylation. Glycosylation is also present in the cytoplasm and nucleus as the ''O''-GlcNAc modification. Aglycosylation is a feature of engineered antibodies to bypass glycosylation. Five classes of glycans are produced: * ''N''-linked glycans attached to a nitrogen of asparagi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-linked Glycosylation
''N''-linked glycosylation is the attachment of an oligosaccharide, a carbohydrate consisting of several sugar molecules, sometimes also referred to as glycan, to a nitrogen atom (the amide nitrogen of an asparagine (Asn) residue of a protein), in a process called ''N''-glycosylation, studied in biochemistry. The resulting protein is called an N-linked glycan, or simply an N-glycan. This type of linkage is important for both the structure and function of many eukaryotic proteins. The ''N''-linked glycosylation process occurs in eukaryotes and widely in archaea, but very rarely in bacteria. The nature of ''N''-linked glycans attached to a glycoprotein is determined by the protein and the cell in which it is expressed. It also varies across species. Different species synthesize different types of ''N''-linked glycans. Energetics of bond formation There are two types of bonds involved in a glycoprotein: bonds between the saccharides residues in the glycan and the linkage between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epimer
In stereochemistry, an epimer is one of a pair of diastereomers. The two epimers have opposite configuration at only one stereogenic center out of at least two. All other stereogenic centers in the molecules are the same in each. Epimerization is the interconversion of one epimer to the other epimer. Doxorubicin and epirubicin are two epimers that are used as drugs. Examples The stereoisomers β-D- glucopyranose and β-D- mannopyranose are epimers because they differ only in the stereochemistry at the C-2 position. The hydroxy group in β-D-glucopyranose is equatorial (in the "plane" of the ring), while in β-D-mannopyranose the C-2 hydroxy group is axial (up from the "plane" of the ring). These two molecules are epimers but, because they are not mirror images of each other, are not enantiomers. (Enantiomers have the same name, but differ in D and L classification.) They are also not sugar anomers, since it is not the anomeric carbon involved in the stereochemistry. Simila ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbohydrate
A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' may differ). This formula does not imply direct covalent bonding between hydrogen and oxygen atoms; for example, in , hydrogen is covalently bonded to carbon, not oxygen. While the 2:1 hydrogen-to-oxygen ratio is characteristic of many carbohydrates, exceptions exist. For instance, uronic acids and deoxy-sugars like fucose deviate from this precise stoichiometric definition. Conversely, some compounds conforming to this definition, such as formaldehyde and acetic acid, are not classified as carbohydrates. The term is predominantly used in biochemistry, functioning as a synonym for saccharide (), a group that includes sugars, starch, and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hepatoma
Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer in adults and is currently the most common cause of death in people with cirrhosis. HCC is the third leading cause of cancer-related deaths worldwide. HCC most commonly occurs in those with chronic liver disease especially those with cirrhosis or fibrosis, which occur in the setting of chronic liver injury and inflammation. HCC is rare in those without chronic liver disease. Chronic liver diseases which greatly increase the risk of HCC include hepatitis infection such as (hepatitis B, C or D), non-alcoholic steatohepatitis (NASH), alcoholic liver disease, or exposure to toxins such as aflatoxin, or pyrrolizidine alkaloids. Certain diseases, such as hemochromatosis and alpha 1-antitrypsin deficiency, markedly increase the risk of developing HCC. The five-year survival in those with HCC is 18%. As with any cancer, the treatment and prognosis of HCC varies depending on tumor histology, size, how ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Culture
Cell culture or tissue culture is the process by which cell (biology), cells are grown under controlled conditions, generally outside of their natural environment. After cells of interest have been Cell isolation, isolated from living tissue, they can subsequently be maintained under carefully controlled conditions. They need to be kept at body temperature (37 °C) in an incubator. These conditions vary for each cell type, but generally consist of a suitable vessel with a substrate or rich growth medium, medium that supplies the essential nutrients (amino acids, carbohydrates, vitamins, minerals), growth factors, hormones, and gases (Carbon dioxide, CO2, Oxygen, O2), and regulates the physio-chemical environment (Buffer solution, pH buffer, osmotic pressure, temperature). Most cells require a surface or an artificial substrate to form an adherent culture as a monolayer (one single-cell thick), whereas others can be grown free floating in a medium as a suspension culture. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Furanose
A furanose is a collective term for carbohydrates that have a chemical structure that includes a five-membered ring system consisting of four carbon atoms and one oxygen atom. The name derives from its similarity to the oxygen heterocycle furan, but the furanose ring does not have double bonds. Structural properties The furanose ring is a cyclic hemiacetal of an aldopentose or a cyclic hemiketal of a ketohexose. A furanose ring structure consists of four carbon and one oxygen atom with the anomeric carbon to the right of the oxygen. The highest numbered chiral carbon (typically to the left of the oxygen in a Haworth projection) determines whether or not the structure has a -configuration or L-configuration. In an -configuration furanose, the substituent on the highest numbered chiral carbon is pointed downwards out of the plane, and in a D-configuration furanose, the highest numbered chiral carbon is facing upwards. The furanose ring will have either alpha or beta config ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
