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Abrin
Abrin is an extremely toxic toxalbumin found in the seeds of the rosary pea (or jequirity pea), '' Abrus precatorius''. It has a median lethal dose of 0.7 micrograms per kilogram of body mass when given to mice intravenously (approximately 3.86 times more toxic than ricin, being 2.7 micrograms per kilogram). The median toxic dose for humans ranges from 10 to 1000 micrograms per kilogram when ingested and is 3.3 micrograms per kilogram when inhaled. Abrin is a ribosome inhibiting protein like ricin, a toxin which can be found in the seeds of the castor oil plant, and pulchellin, a toxin which can be found in the seeds of '' Abrus pulchellus''. Abrin is classed as a " select agent" under U.S. law. Occurrence Abrin is only formed in nature by the rosary pea. The brightly coloured seeds of this plant contain about 0.08% of abrin. The toxin is found within the seeds, and its release is prevented by the seed coat. If the seed coat is injured or destroyed (by chewing, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jequirity
''Abrus precatorius'', commonly known as jequirity bean or rosary pea, is a herbaceous flowering plant in the bean family Fabaceae. It is a slender, perennial climber with long, pinnate-leafleted leaves that twines around trees, shrubs, and hedges. The plant is best known for its seeds, which are used as beads and in percussion instruments, and which are toxic because of the presence of abrin. Ingestion of a single seed, well chewed, can be fatal to both adults and children. The plant is native to Asia and Australia. It has a tendency to become weedy and invasive where it has been introduced. Names ''Abrus precatorius'' is commonly known as jequirity, Crab's eye, or rosary pea, paternoster pea, love pea, precatory pea or bean, prayer bead, John Crow Bead, coral bead, red-bead vine, country licorice, Indian licorice, wild licorice, Jamaica wild licorice, olinda (In Sri Lanka/Sinhala), kundumani (in Tamil), coondrimany, gidee gidee, Jumbie bead,Mendes (1986), p. 79. ratti (in Hind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribosome Inactivating Protein
A ribosome-inactivating protein (RIP) is a protein synthesis inhibitor that acts at the eukaryotic ribosome. This protein family describes a large family of such proteins that work by acting as rRNA N-glycosylase (EC 3.2.2.22). They inactivate 60S ribosomal subunits by an N-glycosidic cleavage, which releases a specific adenine base from the sugar-phosphate backbone of 28S rRNA. RIPs exist in bacteria and plants. Members of the family include shiga toxins, and type I (e.g. trichosanthin and luffin) and type II (e.g. ricin, agglutinin, and abrin) ribosome inactivating proteins (RIPs). All these toxins are structurally related. RIPs have been of considerable interest because of their potential use, conjugated with monoclonal antibodies, as immunotoxins to treat cancers. Further, trichosanthin has been shown to have potent activity against HIV-1-infected T cells and macrophages. Elucidation of the structure-function relationships of RIPs has therefore become a major research effor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lectin
Lectins are carbohydrate-binding proteins that are highly specific for sugar Moiety (chemistry), groups that are part of other molecules, so cause agglutination (biology), 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 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 monosaccharides, mono- and oligosaccharides, which bind to ingested lectins from grains, legumes, nightshade plants, and dairy; binding can prevent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Median Lethal Dose
In toxicology, the median lethal dose, LD50 (abbreviation for " lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a given substance. The value of LD50 for a substance is the dose required to kill half the members of a tested population after a specified test duration. LD50 figures are frequently used as a general indicator of a substance's acute toxicity. A lower LD50 is indicative of higher toxicity. The term LD50 is generally attributed to John William Trevan. The test was created by J. W. Trevan in 1927. The term semilethal dose is occasionally used in the same sense, in particular with translations of foreign language text, but can also refer to a sublethal dose. LD50 is usually determined by tests on animals such as laboratory mice. In 2011, the U.S. Food and Drug Administration approved alternative methods to LD50 for testing the cosmetic drug botox without animal tests. Conventions The LD50 is usually expr ... [...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 one milligram per kilogram of body weight. Ricin is a toxalbumin and was first described by Peter Hermann Stillmark, the founder of lectinology. Ricin is chemically similar to Robin (toxin), robin. 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 ... [...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] |
Disulfide Bridge
In chemistry, a disulfide (or disulphide in British English) is a compound containing a functional group or the anion. The linkage is also called an SS-bond or sometimes a disulfide bridge and usually derived from two thiol groups. In inorganic chemistry, the anion appears in a few rare minerals, but the functional group has tremendous importance in biochemistry. Disulfide bridges formed between thiol groups in two cysteine residues are an important component of the tertiary and quaternary structure of proteins. Compounds of the form are usually called '' persulfides'' instead. Organic disulfides Structure Disulfides have a C–S–S–C dihedral angle approaching 90°. The S–S bond length is 2.03 Å in diphenyl disulfide, similar to that in elemental sulfur. Disulfides are usually symmetric but they can also be unsymmetric. Symmetrical disulfides are compounds of the formula . Most disulfides encountered in organosulfur chemistry are symmetrical disulfides. Unsym ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endoplasmic Reticulum
The endoplasmic reticulum (ER) is a part of a transportation system of the eukaryote, eukaryotic cell, and has many other important functions such as protein folding. The word endoplasmic means "within the cytoplasm", and reticulum is Latin for "little net". It is a type of organelle made up of two subunits – rough endoplasmic reticulum (RER), and smooth endoplasmic reticulum (SER). The endoplasmic reticulum is found in most eukaryotic cells and forms an interconnected network of flattened, membrane-enclosed sacs known as cisternae (in the RER), and tubular structures in the SER. The membranes of the ER are continuous with the outer nuclear membrane. The endoplasmic reticulum is not found in red blood cells, or spermatozoa. There are two types of ER that share many of the same proteins and engage in certain common activities such as the synthesis of certain lipids and cholesterol. Different types of Cell (biology), cells contain different ratios of the two types of ER dependin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ricinus Communis
''Ricinus communis'', the castor bean or castor oil plant, is a species of perennial flowering plant in the spurge family, Euphorbiaceae. It is the sole species in the monotypic genus, ''Ricinus'', and subtribe, Ricininae. The evolution of castor and its relation to other species are currently being studied using modern genetic tools. It reproduces with a mixed pollination system which favors selfing by geitonogamy but at the same time can be an out-crosser by anemophily (wind pollination) or entomophily (insect pollination). Its seed is the castor bean, which despite the term is not a bean (as it is not the seed of a member of the family Fabaceae). Castor is indigenous to the southeastern Mediterranean Basin, East Africa, and India, but is widespread throughout tropical regions (and widely grown elsewhere as an ornamental plant). Castor seed is the source of castor oil, which has a wide variety of uses. The seeds contain between 40% and 60% oil that is rich in triglycerides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seed Coat
In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be sown, which may include seed and husk or tuber. Seeds are the product of the ripened ovule, after the embryo sac is fertilized by sperm from pollen, forming a zygote. The embryo within a seed develops from the zygote and grows within the mother plant to a certain size before growth is halted. The formation of the seed is the defining part of the process of reproduction in seed plants (spermatophytes). Other plants such as ferns, mosses and liverworts, do not have seeds and use water-dependent means to propagate themselves. Seed plants now dominate biological niches on land, from forests to grasslands both in hot and cold climates. In the flowering plants, the ovary ripens into a fruit which contains the seed and serves to disseminate it. Many structures commonly referred to as "seeds" are actual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
