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Digoxigenin
Digoxigenin (DIG) is a steroid found exclusively in the flowers and leaves of the plants ''Digitalis purpurea'', ''Digitalis orientalis'' and ''Digitalis lanata'' (foxgloves), where it is attached to sugars, to form the glycosides (e.g. Lanatoside C). Use in biotechnology Digoxigenin is a hapten, a small molecule with high antigenicity, that is used in many molecular biology applications similarly to other popular haptens such as 2,4-Dinitrophenol, biotin, and fluorescein. Typically, digoxigenin is introduced chemically (conjugation) into biomolecules (proteins, nucleic acids) to be detected in further assays. Kd of the digoxigenin-antibody interaction has been estimated at ~12 nM (compare to Kd~0.1pM for the biotin-streptavidin interaction). DIG-binding proteins. Tinberg et al. designed artificial proteins that bind DIG. Their best binder, DIG10.3, was a 141 amino acid protein that bound DIG with a dissociation constant (Kd) of 541 (+/- 193) pM. Anti-digoxigenin antibo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
In Situ Hybridization
''In situ'' hybridization (ISH) is a type of hybridization that uses a labeled complementary DNA, RNA or modified nucleic acids strand (i.e., probe) to localize a specific DNA or RNA sequence in a portion or section of tissue (''in situ'') or if the tissue is small enough (e.g., plant seeds, ''Drosophila'' embryos), in the entire tissue (whole mount ISH), in cells, and in circulating tumor cells (CTCs). This is distinct from immunohistochemistry, which usually localizes proteins in tissue sections. In situ hybridization is used to reveal the location of specific nucleic acid sequences on chromosomes or in tissues, a crucial step for understanding the organization, regulation, and function of genes. The key techniques currently in use include ''in situ'' hybridization to mRNA with oligonucleotide and RNA probes (both radio-labeled and hapten-labeled), analysis with light and electron microscopes, whole mount ''in situ'' hybridization, double detection of RNAs and RNA plus prote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardenolides
A cardenolide is a type of steroid. Many plants contain derivatives, collectively known as cardenolides, including many in the form of cardenolide glycosides (cardenolides that contain structural groups derived from sugars). Cardenolide glycosides are often toxic; specifically, they are heart-arresting. Cardenolides are toxic to animals through inhibition of the enzyme Na+/K+‐ATPase, which is responsible for maintaining the sodium and potassium ion gradients across the cell membranes. Etymology The term derives from ''card-'' "heart" (from Greek καρδία ''kardiā'') and the suffix ''-enolide'', referring to the lactone ring at C17. Cardenolides are a class of steroids (or aglycones if viewed as cardiac glycoside constituents), and cardenolides are a subtype of this class (see MeSH D codes list). Structure Cardenolides are C(23)-steroids with methyl groups at C-10 and C-13 and a five-membered lactone (specifically a butenolide) at C-17. They are aglycone constituents of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digitalis Lanata
''Digitalis lanata'', vernacularly often called woolly foxglove or Grecian foxglove, is a species of foxglove, a flowering plant in the plantain family Plantaginaceae. It gets its name due to the woolly indumentum of the leaves. ''D. lanata'', like other foxglove species, is toxic in all parts of the plant. Symptoms of digitalis poisoning include nausea, vomiting, severe headache, dilated pupils, problems with eyesight, and convulsions at the worst level of toxicity. The plant is also harmful to other animals. Description ''Digitalis lanata'' is a biennial or perennial growing from a woody, horizontal rootstock. There is a tidy rosette before the spike goes up, and it is neatly arranged around the purple-tinged stems. The plant commonly forms a single, upright, more or less uniformly leafy stem that is partly ascending at the base. The plant send up these stems and flowers in usually in its second year. The stems are 0.3 to 0.6 meters in height, or about 13 to 26 inches. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanatoside C
Lanatoside C (or isolanid) is a cardiac glycoside, a type of drug that can be used in the treatment of congestive heart failure and cardiac arrhythmia (irregular heartbeat). Lanatoside C can be used orally or by the intravenous route. It is marketed in a number of countries and is also available in generic form. Its main indications are rapid response atrial fibrilation and paroxysmal supraventricular tachycardia, two common types of arrhythmia. It is found in ''Digitalis lanata''. Chemistry The substance is composed of four monosaccharides (glucose, 3-acetyldigitoxose and two digitoxoses) and an aglycon named digoxigenin Digoxigenin (DIG) is a steroid found exclusively in the flowers and leaves of the plants '' Digitalis purpurea'', '' Digitalis orientalis'' and '' Digitalis lanata'' (foxgloves), where it is attached to sugars, to form the glycosides (e.g. Lana .... References {{Cardiac glycosides Cardenolides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hapten
In immunology, haptens are small molecules that elicit an immune response only when attached to a large carrier such as a protein; the carrier may be one that also does not elicit an immune response by itself (in general, only large molecules, infectious agents, or insoluble foreign matter can elicit an immune response in the body). Once the body has generated antibodies to a hapten-carrier adduct, the small-molecule hapten may also be able to bind to the antibody, but it will usually not initiate an immune response; usually only the hapten-carrier adduct can do this. Sometimes the small-molecule hapten can even block immune response to the hapten-carrier adduct by preventing the adduct from binding to the antibody, a process called ''hapten inhibition''. The mechanisms of absence of immune response may vary and involve complex immunological mechanisms, but can include absent or insufficient co-stimulatory signals from antigen-presenting cells. Haptens have been used to study al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescein
Fluorescein is an organic compound and dye based on the xanthene tricyclic structural motif, formally belonging to triarylmethine dyes family. It is available as a dark orange/red powder slightly soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications. The color of its aqueous solutions is green by reflection and orange by transmission (its spectral properties are dependent on pH of the solution), as can be noticed in bubble levels, for example, in which fluorescein is added as a colorant to the alcohol filling the tube in order to increase the visibility of the air bubble contained within (thus enhancing the precision of the instrument). More concentrated solutions of fluorescein can even appear red (because under these conditions nearly all incident emission is re-absorbed by the solution). It is on the World Health Organization's List of Essential Medicines. Uses Fluorescein sodium, the sodium salt of fluorescein, is used extensi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ELISA
The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence of a ligand (commonly a protein) in a liquid sample using antibodies directed against the protein to be measured. ELISA has been used as a diagnostic tool in medicine, plant pathology, and biotechnology, as well as a quality control check in various industries. In the most simple form of an ELISA, antigens from the sample to be tested are attached to a surface. Then, a matching antibody is applied over the surface so it can bind the antigen. This antibody is linked to an enzyme and then any unbound antibodies are removed. In the final step, a substance containing the enzyme's substrate is added. If there was binding, the subsequent reaction produces a detectable signal, most commonly a color change. Performing an ELISA involves at least ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunostaining
In biochemistry, immunostaining is any use of an antibody-based method to detect a specific protein in a sample. The term "immunostaining" was originally used to refer to the immunohistochemical staining of tissue sections, as first described by Albert Coons in 1941. However, immunostaining now encompasses a broad range of techniques used in histology, cell biology, and molecular biology that use antibody-based staining methods. Techniques Immunohistochemistry Immunohistochemistry or IHC staining of tissue sections (or immunocytochemistry, which is the staining of cells), is perhaps the most commonly applied immunostaining technique. While the first cases of IHC staining used fluorescent dyes (see '' immunofluorescence''), other non-fluorescent methods using enzymes such as peroxidase (see '' immunoperoxidase staining'') and alkaline phosphatase are now used. These enzymes are capable of catalysing reactions that give a coloured product that is easily detectable by light m ... [...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 (though in practice, 'glycation' often refers more specifically to Maillard-type reactions). 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 clas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monosaccharide
Monosaccharides (from Greek ''monos'': single, '' sacchar'': sugar), also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built. They are usually colorless, water-soluble, and crystalline solids. Contrary to their name (sugars), only some monosaccharides have a sweet taste. Most monosaccharides have the formula (though not all molecules with this formula are monosaccharides). Examples of monosaccharides include glucose (dextrose), fructose (levulose), and galactose. Monosaccharides are the building blocks of disaccharides (such as sucrose and lactose) and polysaccharides (such as cellulose and starch). The table sugar used in everyday vernacular is itself a disaccharide sucrose comprising one molecule of each of the two monosaccharides D-glucose and D-fructose. Each carbon atom that supports a hydroxyl group is chiral, except those at the end of the chain. This gives rise to a number of isomeric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Detection Limit
The limit of detection (LOD or LoD) is the lowest signal, or the lowest corresponding quantity to be determined (or extracted) from the signal, that can be observed with a sufficient degree of confidence or statistical significance. However, the exact threshold (level of decision) used to decide when a signal significantly emerges above the continuously fluctuating background noise remains arbitrary and is a matter of policy and often of debate among scientists, statisticians and regulators depending on the stakes in different fields. Significance in analytical chemistry In analytical chemistry, the detection limit, lower limit of detection, or LOD (limit of detection), often mistakenly confused with the analytical sensitivity, is the lowest quantity of a substance that can be distinguished from the absence of that substance (a '' blank value'') with a stated confidence level (generally 99%). The detection limit is estimated from the mean of the blank, the standard deviation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Riboprobe
A Riboprobe, abbreviation of RNA probe, is a segment of labelled RNA that can be used to detect a target mRNA or DNA during in situ hybridization. RNA probes can be produced by ''in vitro'' transcription of cloned DNA inserted in a suitable plasmid downstream of a viral promoter. Some bacterial viruses code for their own RNA polymerases, which are highly specific for the viral promoters. Using these enzymes, labeled NTPs, and inserts inserted in both forward and reverse orientations, both sense and antisense riboprobes can be generated from a cloned gene. Since James Watson and Francis Crick revealed the double helix nature of DNA molecule (Watson & Crick, 1953), the hydrogen bonds between the four bases are well known: adenine always binds to thymine and cytosine always binds to guanine. This binding pattern is the basic principle of modern genetic technologies. Joseph Gall and Mary Lou Pardue published a paper in 1969 demonstrating that radioactive marked ribosomal DNA can be us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
