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Lectin
Lectins are carbohydrate-binding proteins that are highly specific for sugar groups that are part of other molecules, so cause agglutination of particular cells or precipitation of glycoconjugates and polysaccharides. Lectins have a role in recognition at the cellular and molecular level and play numerous roles in biological recognition phenomena involving cells, carbohydrates, and proteins. Lectins also mediate attachment and binding of bacteria, viruses, and fungi to their intended targets. Lectins are ubiquitous in nature and are found in many foods. Some foods, such as beans and grains, need to be cooked, fermented or sprouted to reduce lectin content. Some lectins are beneficial, such as CLEC11A, which promotes bone growth, while others may be powerful toxins such as ricin. Lectins may be disabled by specific mono- and oligosaccharides, which bind to ingested lectins from grains, legumes, nightshade plants, and dairy; binding can prevent their attachment to the carbohyd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concanavalin A
Concanavalin A (ConA) is a lectin (carbohydrate-binding protein) originally extracted from the jack-bean (''Canavalia ensiformis''). It is a member of the legume lectin family. It binds specifically to certain structures found in various sugars, glycoproteins, and glycolipids, mainly internal and nonreducing terminal α-D- mannosyl and α-D-glucosyl groups. Its physiological function in plants, however, is still unknown. ConA is a plant mitogen, and is known for its ability to stimulate mouse T-cell subsets giving rise to four functionally distinct T cell populations, including precursors to regulatory T cells; a subset of human suppressor T-cells is also sensitive to ConA. ConA was the first lectin to be available on a commercial basis, and is widely used in biology and biochemistry to characterize glycoproteins and other sugar-containing entities on the surface of various cells. It is also used to purify glycosylated macromolecules in lectin affinity chromatography, as well ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ricin
Ricin ( ) is a lectin (a carbohydrate-binding protein) and a highly potent toxin produced in the seeds of the castor oil plant, ''Ricinus communis''. The median lethal dose (LD50) of ricin for mice is around 22 micrograms per kilogram of body weight via intraperitoneal injection. Oral exposure to ricin is far less toxic. An estimated lethal oral dose in humans is approximately 1 milligram per kilogram of body weight. Ricin was first described by Peter Hermann Stillmark, the founder of lectinology. Biochemistry Ricin is classified as a type 2 ribosome-inactivating protein (RIP). Whereas type 1 RIPs are composed of a single protein chain that possesses catalytic activity, type 2 RIPs, also known as holotoxins, are composed of two different protein chains that form a heterodimeric complex. Type 2 RIPs consist of an A chain that is functionally equivalent to a type 1 RIP, covalently connected by a single disulfide bond to a B chain that is catalytically inactive, but se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ricin
Ricin ( ) is a lectin (a carbohydrate-binding protein) and a highly potent toxin produced in the seeds of the castor oil plant, ''Ricinus communis''. The median lethal dose (LD50) of ricin for mice is around 22 micrograms per kilogram of body weight via intraperitoneal injection. Oral exposure to ricin is far less toxic. An estimated lethal oral dose in humans is approximately 1 milligram per kilogram of body weight. Ricin was first described by Peter Hermann Stillmark, the founder of lectinology. Biochemistry Ricin is classified as a type 2 ribosome-inactivating protein (RIP). Whereas type 1 RIPs are composed of a single protein chain that possesses catalytic activity, type 2 RIPs, also known as holotoxins, are composed of two different protein chains that form a heterodimeric complex. Type 2 RIPs consist of an A chain that is functionally equivalent to a type 1 RIP, covalently connected by a single disulfide bond to a B chain that is catalytically inactive, but se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peanut Agglutinin
Peanut agglutinin (PNA) is plant lectin protein derived from the fruits of ''Arachis hypogaea''. Peanut agglutinin may also be referred to as ''Arachis hypogaea'' lectin. Lectins recognise and bind particular sugar sequences in carbohydrates; peanut agglutinin binds the carbohydrate sequence Gal-β(1-3)- GalNAc. The name "peanut agglutinin" originates from its ability to stick together ( agglutinate) cells, such as neuraminidase-treated erythrocytes, which have glycoproteins or glycolipids on their surface which include the Gal-β(1-3)-GalNAc carbohydrate sequence. Structure The protein is 273 amino acids in length with the first 23 residues acting as a signal peptide which is subsequently cleaved. It has a Uniprot accession oP02872 There are over 20 structures of this protein in the PDB which reveal and all beta-sheet protein with a tetrameric quaternary structure. It is a member of the Lectin_legB PFAM family.Available Structures of peanut agglutinin Uses in cell biology and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jacalin
Jacalin is a plant-based lectin, but not a legume lectin, found in jackfruit. It has been studied for capturing O-glycoproteins such as mucins and IgA1, for potential applications in human immunology. Jacalin belongs to a family of galactose-binding lectins containing the Jacalin-like lectin domain and it has a tetrameric two-chain structure with a weight of 66 kDa Jacalin is preferably used in applications to isolate IgA from human serum, isolating human plasma glycoproteins and for applications in histochemistry. The lectin is blood group non-specific after neuraminidase treatment and agglutinates human erythrocytes at a concentration of ≥ 7,8 µg/ml. A post-translational proteolytic modification of Jacalin gives the lectin a novel carbohydrate-binding site involving the N-terminus of the a-chain. The relative affinities of the lectin for galactose derivatives, as well as the structural basis of its T-antigen specificity, are explained by its protein structure See also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CLEC11A
C-type lectin domain family 11 member A is a protein that in humans is encoded by the ''CLEC11A'' gene. Function This gene encodes a member of the C-type lectin superfamily. The encoded protein is a secreted sulfated glycoprotein and functions as a growth factor for primitive hematopoietic progenitor cell A progenitor cell is a biological cell that can differentiate into a specific cell type. Stem cells and progenitor cells have this ability in common. However, stem cells are less specified than progenitor cells. Progenitor cells can only differ ...s. An alternative splice variant has been described but its biological nature has not been determined. References Further reading * * * * * * * * * External links * {{gene-19-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligosaccharides
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 maltodext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galanthus Nivalis
''Galanthus nivalis'', the snowdrop or common snowdrop, is the best-known and most widespread of the 20 species in its genus, ''Galanthus''. Snowdrops are among the first bulbs to bloom in spring and can form impressive carpets of white in areas where they are native or have been naturalised. They should not be confused with the snowflakes, in the genera ''Leucojum'' and '' Acis''. Naming The generic name ''Galanthus'', from the Greek ''gala'' (milk) and ''anthos'' (flower), was given to the genus by Carl Linnaeus in 1735. He described ''Galanthus nivalis'' in his ' published in 1753. The epithet means "of the snow", referring either to the snow-like flower or the plant's early flowering. The common name snowdrop first appeared in the 1633 edition of John Gerard's ''Great Herbal'' (in the first edition (1597) he described it as the "Timely flowring Bulbus violet"). The derivation of the name is uncertain, although it may have come from the German word ''Schneetropfen'', which wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galactose
Galactose (, '' galacto-'' + ''-ose'', "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epimer of glucose. A galactose molecule linked with a glucose molecule forms a lactose molecule. Galactan is a polymeric form of galactose found in hemicellulose, and forming the core of the galactans, a class of natural polymeric carbohydrates. D-Galactose is also known as brain sugar since it is a component of glycoproteins (oligosaccharide-protein compounds) found in nerve tissue. Etymology The word ''galactose'' was coined by Charles Weissman in the mid-19th century and is derived from Greek ''galaktos'' (of milk) and the generic chemical suffix for sugars ''-ose''. The etymology is comparable to that of the word ''lactose'' in that both contain roots meaning "milk sugar". Lactose is a disaccharide of galactose plus glucose. Structure and isomerism Galactose exists in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canavalia Ensiformis
''Canavalia ensiformis'' (jack bean) is a legume which is used for animal fodder and human nutrition, especially in Brazil where it is called ''feijão-de-porco'' ("pig bean"). It is also the source of concanavalin A. Description ''C. ensiformis'' is a twining plant up to in height. It has deep roots, which makes it drought resistant. The plant can spread via long runners. The flowers are pink-purple in colour. The pods are up to long with large white seeds. Uses The plant is not in large-scale commercial cultivation. The beans are mildly toxic, and copious consumption should be avoided. Boiling will, however, remove toxicity if done properly. Young foliage is also edible. The whole plant is used for fodder, although it cannot be used in fodder mixtures containing urea, since it contains large quantities of the enzyme urease, which liberates harmful ammonia from urea. For this reason ''C. ensiformis'' has been investigated as a potential source of the urease enzyme. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-acetylglucosamine
''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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
