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Ribosome-inactivating Protein
A ribosome-inactivating protein (RIP) is a protein synthesis inhibitor that acts at the eukaryote, 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 antibody, 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 b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Protein Synthesis Inhibitor
A protein synthesis inhibitor is a compound that stops or slows the growth or proliferation of cells by disrupting the processes that lead directly to the generation of new proteins. While a broad interpretation of this definition could be used to describe nearly any compound depending on concentration, in practice, it usually refers to compounds that act at the molecular level on translational machinery (either the ribosome itself or the translation factor), taking advantages of the major differences between prokaryotic and eukaryotic ribosome structures. Mechanism In general, protein synthesis inhibitors work at different stages of bacterial translation, bacterial mRNA translation into proteins, like initiation, elongation (including aminoacyl tRNA entry, Proofreading (biology), proofreading, peptidyl transfer, and bacterial translation#Elongation, bacterial translocation) and termination: Earlier stages * Rifamycin inhibits Bacterial transcription, bacterial DNA transcription ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Macrophage
Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that are specific to healthy body cells on their surface. This self-protection method can be contrasted with that employed by Natural killer cell, Natural Killer cells. This process of engulfment and digestion is called phagocytosis; it acts to defend the host against infection and injury. Macrophages are found in essentially all tissues, where they patrol for potential pathogens by amoeboid movement. They take various forms (with various names) throughout the body (e.g., histiocytes, Kupffer cells, alveolar macrophages, microglia, and others), but all are part of the mononuclear phagocyte system. Besides phagocytosis, they play a critical role in nonspecific defense (innate immunity) and also help initiate specific defense mechanisms (adapti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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] [Amazon] |
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] [Amazon] |
Spiroplasma
''Spiroplasma'' is a genus of Mollicutes, a group of small bacteria without cell walls. ''Spiroplasma'' shares the simple metabolism, parasitic lifestyle, fried-egg colony morphology and small genome of other ''Mollicutes'', but has a distinctive helical morphology, unlike ''Mycoplasma''. It has a spiral shape and moves in a corkscrew motion. Many ''Spiroplasma'' are found either in the gut or haemolymph of insects where they can act to manipulate host reproduction, or defend the host as endosymbionts. ''Spiroplasma'' are also disease-causing agents in the phloem of plants. Spiroplasmas are fastidious organisms, which require a rich culture medium. Typically they grow well at 30 °C, but not at 37 °C. A few species, notably '' Spiroplasma mirum'', grow well at 37 °C (human body temperature), and cause cataracts and neurological damage in suckling mice. The best studied species of spiroplasmas are '' Spiroplasma poulsonii'', a reproductive manipulator and defensi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Trichosanthin
Trichosanthin is a ribosome-inactivating protein. It is derived from ''Trichosanthes kirilowii''. It is also an abortifacient An abortifacient ("that which will cause a miscarriage" from Latin: '' abortus'' "miscarriage" and '' faciens'' "making") is a substance that induces abortion. This is a nonspecific term which may refer to any number of substances or medications, .... References External links * Proteins Ribosome-inactivating proteins {{pharmacology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Phytolacca Americana
''Phytolacca americana'', also known as American pokeweed, pokeweed, poke sallet, pokeberry, dragonberries, pigeonberry weed, and inkberry, is a List of poisonous plants, poisonous, herbaceous perennial plant in the pokeweed family Phytolaccaceae. This pokeweed grows . It has simple leaves on green to red or purplish Plant stem, stems and a large white taproot. The flowers are green to white, followed by berries which ripen through red to purple to almost black which are a food source for songbirds such as grey catbird, gray catbird, northern mockingbird, northern cardinal, and brown thrasher, as well as other birds and some small non-avian animals (i.e., for species that are unaffected by its mammalian toxins). Pokeweed is native to eastern North America, the Midwest, and the South, with more scattered populations in the far West where it was introduced. It is also naturalized in parts of Europe and Asia. It is considered a Pest (organism), pest species by farmers. Pokeweed is po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Pokeweed Antiviral Protein
''Phytolacca'' is a genus of perennial plants native to North America, South America and East Asia. Some members of the genus are known as pokeweeds or similar names such as pokebush, pokeberry, pokeroot or poke sallet. Other names for species of ''Phytolacca'' include inkberry and ombú. The generic name is derived from the Greek language, Greek word (''phyton''), meaning "plant," and the Latin word ''Lac (resin), lacca'', a red dye. Phytolaccatoxin and phytolaccagenin are present (in the leaves, stems, roots, blossoms, berries etc.) in many species which are poisonous to mammals if not prepared properly. The berries are eaten by birds, which are not affected by the toxin. The small seeds with very hard outer shells remain intact in the digestive system and are eliminated whole. The genus comprises about 25 to 35 species of perennial plant, perennial herbaceous plant, herbs, shrubs, and trees growing from tall. They have alternate simple leaves, pointed at the end, with entir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Saporin
Saporin is a protein that is useful in biological research applications, especially studies of behavior. Saporins are so-called ribosome inactivating proteins (RIPs), due to its N-glycosidase activity, from the seeds of ''Saponaria officinalis'' (common name: soapwort). It was first described by Fiorenzo Stirpe and his colleagues in 1983 in an article that illustrated the unusual stability of the protein. Among the RIPs are some of the most toxic molecules known, such as ricin and abrin. Each of these toxins contain a second protein subunit, which inserts the RIP into a cell, enabling it to enzymatically inactivate the ribosomes, shutting down protein synthesis, stopping basic cell functions, resulting in cell death, and eventually causing death of the victim. Saporin has no chain capable of inserting it into the cell. Thus it and the soapwort plant are safe to handle. This has aided its use in research. If given a method of entry into the cell, saporin becomes a very potent to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Beetin
Beetin (BE27 or BE29) is a ribosome-inactivating protein found in the leaves of sugar beets, ''Beta vulgaris'' L, specifically attacking plant ribosomes. Sugar beet, beetins, that have been isolated meet all the criteria to be classified as single chain (type 1) ribosome inactivating proteins that are highly toxic to mammalian ribosomes but non-toxic to intact cultured mammalian cells. Beetin expression occurs when there is a viral infection of the plant. The different levels of glycosylation of the same polypeptide chain result in the two forms of beetin (BE27 or BE29). Beetin exhibits these two primary forms with apparent Mr values of 27 000 (BE27) and 29 000 (BE29) along with possessing glycan chains. Beetins are a type-I (single-chain) proteins with N-glycoside activity. Since it has been discovered that beetin is mostly concentrated in the intercellular fluid, its presence in the remaining parts of the leaf may be below the limit of detection rather than being nonexistent. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
AB5 Toxin
The AB5 toxins are six-component protein complexes secreted by certain pathogenic bacteria known to cause human diseases such as cholera, dysentery, and hemolytic–uremic syndrome. One component is known as the A subunit, and the remaining five components are B subunits. All of these toxins share a similar structure and mechanism for entering targeted host cells. The B subunit is responsible for binding to receptors to open up a pathway for the A subunit to enter the cell. The A subunit is then able to use its catalytic machinery to take over the host cell's regular functions. Families There are four main families of the AB5 toxin. These families are characterized by the sequence of their A (catalytic) subunit, as well as their catalytic activity. Cholera toxin This family is also known as Ct or Ctx, and also includes the heat-labile enterotoxin, known as LT. Cholera toxin's discovery is credited by many to Dr. Sambhu Nath De. He conducted his research in Calcutta (now ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
