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Enterobacterial Common Antigen
The enterobacterial common antigen (ECA) is a carbohydrate antigen found in the outer membrane of many ''Enterobacterales'' species. The antigen is unanimously absent from other gram-negative and gram-positive bacteria. ''Aeromonas hydrophila 209A'' is the only organism outside of ''Enterobacterales'' that expresses the ECA. More studies are needed to explain the presence of the antigen in this species as no other strains of this species express the antigen. The ECA is a polysaccharide made of repeating units of trisaccharides. The functions of these units have very few proven functions. Some evidence indicates role in pathogenicity in the bacteria that present the ECA. There are three separate types of ECA these include ECAPG, ECALPS, and ECACYC, each have different lengths. The synthesis of the ECA is controlled by the ''wec'' operon and has a 12-step synthesis which is described below. Due to the lack of proven function of the ECA, any clinical significance is hard to define howev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or may not be different from ''n''), which does not mean the H has covalent bonds with O (for example with , H has a covalent bond with C but not with O). However, not all carbohydrates conform to this precise stoichiometric definition (e.g., uronic acids, deoxy-sugars such as fucose), nor are all chemicals that do conform to this definition automatically classified as carbohydrates (e.g. formaldehyde and acetic acid). The term is most common in biochemistry, where it is a synonym of saccharide (), a group that includes sugars, starch, and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides and disaccharides, the smallest (lower molecul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GlcNAc
''N''-Acetylglucosamine (GlcNAc) is an amide derivative of the monosaccharide glucose. It is a secondary amide between glucosamine and acetic acid. It is significant in several biological systems. It is part of a biopolymer in the bacterial cell wall, which is built from alternating units of GlcNAc and ''N''-acetylmuramic acid (MurNAc), cross-linked with oligopeptides at the lactic acid residue of MurNAc. This layered structure is called peptidoglycan (formerly called murein). GlcNAc is the monomeric unit of the polymer chitin, which forms the exoskeletons of arthropods like insects and crustaceans. It is the main component of the radulas of mollusks, the beaks of cephalopods, and a major component of the cell walls of most fungi. Polymerized with glucuronic acid, it forms hyaluronan. GlcNAc has been reported to be an inhibitor of elastase release from human polymorphonuclear leukocytes (range 8–17% inhibition), however this is much weaker than the inhibition seen with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligosaccharide
An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide polymer containing a small number (typically two to ten) of monosaccharides (simple sugars). Oligosaccharides can have many functions including cell recognition and cell adhesion. They are normally present as glycans: oligosaccharide chains are linked to lipids or to compatible amino acid side chains in proteins, by ''N''- or ''O''-glycosidic bonds. ''N''-Linked oligosaccharides are always pentasaccharides attached to asparagine via a beta linkage to the amine nitrogen of the side chain.. Alternately, ''O''-linked oligosaccharides are generally attached to threonine or serine on the alcohol group of the side chain. Not all natural oligosaccharides occur as components of glycoproteins or glycolipids. Some, such as the raffinose series, occur as storage or transport carbohydrates in plants. Others, such as maltodextrin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flippase
Flippases (rarely spelled flipases) are transmembrane lipid transporter proteins located in the membrane which belong to ABC transporter or P4-type ATPase families. They are responsible for aiding the movement of phospholipid molecules between the two leaflets that compose a cell's membrane (transverse diffusion, also known as a "flip-flop" transition). The possibility of active maintenance of an asymmetric distribution of molecules in the phospholipid bilayer was predicted in the early 1970s by Mark Bretscher. Although phospholipids diffuse rapidly in the plane of the membrane, their polar head groups cannot pass easily through the hydrophobic center of the bilayer, limiting their diffusion in this dimension. Some flippases - often instead called scramblases - are energy-independent and bidirectional, causing reversible equilibration of phospholipid between the two sides of the membrane, whereas others are energy-dependent and unidirectional, using energy from ATP hydrolysis to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glutamate
Glutamic acid (symbol Glu or E; the ionic form is known as glutamate) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can synthesize enough for its use. It is also the most abundant excitatory neurotransmitter in the vertebrate nervous system. It serves as the precursor for the synthesis of the inhibitory gamma-aminobutyric acid (GABA) in GABA-ergic neurons. Its molecular formula is . Glutamic acid exists in three optically isomeric forms; the dextrorotatory -form is usually obtained by hydrolysis of gluten or from the waste waters of beet-sugar manufacture or by fermentation.Webster's Third New International Dictionary of the English Language Unabridged, Third Edition, 1971. Its molecular structure could be idealized as HOOC−CH()−()2−COOH, with two carboxyl groups −COOH and one amino group −. However, in the solid state and mildly acidic water solu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's role as a catalyst (a catalyst is a substance that increases the rate of a chemical reaction). Cofactors can be considered "helper molecules" that assist in biochemical transformations. The rates at which these happen are characterized in an area of study called enzyme kinetics. Cofactors typically differ from ligands in that they often derive their function by remaining bound. Cofactors can be divided into two types: inorganic ions and complex organic molecules called coenzymes. Coenzymes are mostly derived from vitamins and other organic essential nutrients in small amounts. (Note that some scientists limit the use of the term "cofactor" for inorganic substances; both types are included here.) Coenzymes are further divided into two types. The first is called a "prosthetic group", which consists of a coenzyme that is tightly (or even covalently) and permanently bound to a prote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isoprenoid Unit
The terpenoids, also known as isoprenoids, are a class of naturally occurring organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeably with "terpenes", terpenoids contain additional functional groups, usually containing oxygen. When combined with the hydrocarbon terpenes, terpenoids comprise about 80,000 compounds. They are the largest class of plant secondary metabolites, representing about 60% of known natural products. Many terpenoids have substantial pharmacological bioactivity and are therefore of interest to medicinal chemists. Plant terpenoids are used for their aromatic qualities and play a role in traditional herbal remedies. Terpenoids contribute to the scent of eucalyptus, the flavors of cinnamon, cloves, and ginger, the yellow color in sunflowers, and the red color in tomatoes. Well-known terpenoids include citral, menthol, camphor, salvinorin A in the plant ''Salv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipid Carrier
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins Vitamin A, A, Vitamin D, D, Vitamin E, E and Vitamin K, K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing energy, lipid signaling, signaling, and acting as structural components of cell membranes. Lipids have applications in the Cosmetic industry, cosmetic and Food industry, food industries, and in nanotechnology. Lipids may be broadly defined as Hydrophobe, hydrophobic or Amphiphile, amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicle (biology), vesicles, multilamellar/unilamellar liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks": :wikt:ketoacyl, ketoacyl and isoprene groups. Using this approach, lipids may be divided i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Undecaprenyl Phosphate
Undecaprenyl phosphate (UP), also known lipid-P, bactoprenol and C55-P., is a molecule with the primary function of trafficking polysaccharides across the cell membrane, largely contributing to the overall structure of the cell wall in Gram-positive bacteria. In some situations, UP can also be utilized to carry other cell-wall polysaccharides, but UP is the designated lipid carrier for peptidoglycan. During the process of carrying the peptidoglycan across the cell membrane, ''N''-acetylglucosamine and ''N''-acetylmuramic acid are linked to UP on the cytoplasmic side of the membrane before being carried across. UP works in a cycle of phosphorylation and dephosphorylation as the lipid carrier gets used, recycled, and reacts with undecaprenyl phosphate. This type of synthesis is referred to as ''de novo'' synthesis where a complex molecule is created from simpler molecules as opposed to a complete recycle of the entire structure. The synthesis of UP differs between Gram-negative an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
