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Photostatin
Photostatins are inhibitors that can be switched on and off ''in vivo'' by visible light, to optically control microtubule dynamics. Photostatins are a form of photopharmacology. As a cell prepares to divide, its microtubules, arrange themselves into a spindle that permits its chromosomes to split into two bundles. These bundles become the nuclei of the daughter cells, Out-of-control cell replication is the underlying cause of cancer, developing drugs that interfere with microtubule activity offers one potential therapeutic approach. They can operate microtubule dynamics with a subsecond response time and control mitosis in living organisms with single-cell spatial precision. Most microtubule inhibitors affect both cancerous and healthy cells, requiring lower doses to avoid severe side effects. Because photostatins are inactive in the absence of light, they only affect cells that are illuminated. Focusing light on tumors directs their activities to appropriate targets with fewer s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microtubule
Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 and 15 nm. They are formed by the polymerization of a dimer of two globular proteins, alpha and beta tubulin into protofilaments that can then associate laterally to form a hollow tube, the microtubule. The most common form of a microtubule consists of 13 protofilaments in the tubular arrangement. Microtubules play an important role in a number of cellular processes. They are involved in maintaining the structure of the cell and, together with microfilaments and intermediate filaments, they form the cytoskeleton. They also make up the internal structure of cilia and flagella. They provide platforms for intracellular transport and are involved in a variety of cellular processes, including the movement of secretory vesicles, organell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photopharmacology
Photopharmacology, an emerging approach in medicine, involves activating and deactivating photoswitchable molecules with light for target drug delivery. Clinicians use the energy of light to change the shape and chemical properties of a drug, resulting in different biological activity. This is done to ultimately achieve control of when and where drugs are active in a reversible manner, and to prevent side effects and exposure to the environment of antibiotics. Switching drugs "on" and "off" is achieved by introducing photoswitches such as azobenzene, spiropyran or diarylethene into the drug. Photopharmalogical drugs with a photoswitch have two different states, which light can toggle between. Since both states have a different structure, the activity of the drug is different, hence the "on" and "off" state of the drug. An example is photostatin, which is an inhibitor that can be switched on and off ''in vivo'' to optically control microtubule dynamics. See also * Optogenetics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosomes
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are the histones. These proteins, aided by chaperone proteins, bind to and condense the DNA molecule to maintain its integrity. These chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation. Chromosomes are normally visible under a light microscope only during the metaphase of cell division (where all chromosomes are aligned in the center of the cell in their condensed form). Before this happens, each chromosome is duplicated (S phase), and both copies are joined by a centromere, resulting either in an X-shaped structure (pictured above), if the centromere is located equatorially, or a two-arm structure, if the centromere is located distally. The joined copies are now called sis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Nucleus
The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support. The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long stands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating gene expres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitosis
In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maintained. Therefore, mitosis is also known as equational division. In general, mitosis is preceded by S phase of interphase (during which DNA replication occurs) and is often followed by telophase and cytokinesis; which divides the cytoplasm, organelles and cell membrane of one cell into two new cells containing roughly equal shares of these cellular components. The different stages of mitosis altogether define the mitotic (M) phase of an animal cell cycle—the division of the mother cell into two daughter cells genetically identical to each other. The process of mitosis is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages are preprophase (specific to plant cells), prophase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combretastatin
Combretastatin is a dihydrostilbenoid found in '' Combretum caffrum''. As a class Combretastatins are a class of natural phenols. A variety of different natural combretastatin molecules are present in the bark of '' Combretum caffrum'', commonly known as South African Bush Willow. Despite having a similar name, combretastatins are unrelated to statins, a family of cholesterol lowering drugs. Natural combretastatins Molecules that fall into the combretastatin family generally share 3 common structural features: a trimethoxy "A"-ring, a "B"-ring containing substituents often at C3' and C4', and ftenan ethene bridge between the two rings which provides necessary structural rigidity. Molecules with such an ethene bridge are also stilbenoids, molecules with a non-ethene bridge are dihydrostilbenoids. Molecules with C3' amino and hydroxyl substituents are very active, and molecules with C4' hydroxyl or methoxy substituents are also cytotoxic. Of the natural products presently kn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South African Bushwillow
''Combretum caffrum'' is the Eastern Cape South African bushwillow tree. Biochemistry In ''C. caffrum'', combretastatins A-1, A-4 and B-1 can be found. References * * caffrum[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties. Two main forms of isomerism are structural or constitutional isomerism, in which ''bonds'' between the atoms differ; and stereoisomerism or spatial isomerism, in which the bonds are the same but the ''relative positions'' of the atoms differ. Isomeric relationships form a hierarchy. Two chemicals might be the same constitutional isomer, but upon deeper analysis be stereoisomers of each other. Two molecules that are the same stereoisomer as each other might be in different conformational forms or be different isotopologues. The depth of analysis depends on the field of study or the chemical and physical properties of interest. The English word "isomer" () is a back-for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photopharmacology
Photopharmacology, an emerging approach in medicine, involves activating and deactivating photoswitchable molecules with light for target drug delivery. Clinicians use the energy of light to change the shape and chemical properties of a drug, resulting in different biological activity. This is done to ultimately achieve control of when and where drugs are active in a reversible manner, and to prevent side effects and exposure to the environment of antibiotics. Switching drugs "on" and "off" is achieved by introducing photoswitches such as azobenzene, spiropyran or diarylethene into the drug. Photopharmalogical drugs with a photoswitch have two different states, which light can toggle between. Since both states have a different structure, the activity of the drug is different, hence the "on" and "off" state of the drug. An example is photostatin, which is an inhibitor that can be switched on and off ''in vivo'' to optically control microtubule dynamics. See also * Optogenetics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
