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N-Formylmethionine-leucyl-phenylalanine
''N''-Formylmethionyl-leucyl-phenylalanine (fMLF, fMLP or ''N''-formyl-met-leu-phe) is an ''N''- formylated tripeptide and sometimes simply referred to as chemotactic peptide is a potent polymorphonuclear leukocyte (PMN) chemotactic factor and is also a macrophage activator. fMLF is the prototypical representative of the ''N''-formylated oligopeptide family of chemotactic factors. These oligopeptides are known to be, or mimic the actions of, the ''N''-formyl oligopeptides that are (a) released by tissue bacteria, (b) attract and activate circulating blood leukocytes by binding to specific G protein coupled receptors on these cells, and (c) thereby direct the inflammatory response to sites of bacterial invasion. fMLF is involved in the innate immunity mechanism for host defense against pathogens. fMLF led to the first discovery of a leukocyte receptor for a chemotactic factor, defined three different types of fMLF receptors that have complementary and/or opposing effects on i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemotactic Factor
Chemotaxis (from '' chemo-'' + ''taxis'') is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. This is important for bacteria to find food (e.g., glucose) by swimming toward the highest concentration of food molecules, or to flee from poisons (e.g., phenol). In multicellular organisms, chemotaxis is critical to early development (e.g., movement of sperm towards the egg during fertilization) and development (e.g., migration of neurons or lymphocytes) as well as in normal function and health (e.g., migration of leukocytes during injury or infection). In addition, it has been recognized that mechanisms that allow chemotaxis in animals can be subverted during cancer metastasis. The aberrant chemotaxis of leukocytes and lymphocytes also contribute to inflammatory diseases such as atherosclerosis, asthma, and art ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Find-me Signals
Find-me signals Cells destined for apoptosis release molecules referred to as find me signals. These signal molecules are used to attract phagocytes which engulf and eliminate damaged cells. Find-me signals are typically released by the apoptotic cells while the cell membrane remains intact. This ensures that the phagocytic cells are able to remove the dying cells before their membranes are compromised. A leaky membrane leads to secondary necrosis which may cause additional inflammation, therefore, it is best to remove dying cells before this occurs. One cell is capable of releasing multiple find-me signals. Should a cell lack the ability to release its find-me signal, other cells may release additional find-me signals to overcome the discrepancy. Additional roles of Find-me signals Inflammation can be suppressed by find-me signals during cell clearance. A phagocyte may also be able to engulf more material or enhance its ability to engulf materials when stimulated by find-me signal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Élie Metchnikoff
Ilya Ilyich Mechnikov (russian: Илья Ильич Мечников; – 15 July 1916), also spelled Élie Metchnikoff, was a Russian zoologist best known for his pioneering research in immunology. Belkin, a Russian science historian, explains why Metchnikoff himself, in his Nobel autobiography – and subsequently, many other sources – mistakenly cited his date of birth as 16 May instead of 15 May. Metchnikoff made the mistake of adding 13 days to 3 May, his Old Style birthday, as was the convention in the 20th century. But since he had been born in the 19th century, only 12 days should have been added. He and Paul Ehrlich were jointly awarded the 1908 Nobel Prize in Physiology or Medicine "in recognition of their work on immunity". Mechnikov was born in modern-day Ukraine to a Romanian noble father and a Ukrainian-Jewish mother, lived and worked for many years on the territory of what was then the Russian Empire, and later on continued his career in France. Given this com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-Formylmethionine
''N''-Formylmethionine (fMet, HCO-Met, For-Met) is a derivative of the amino acid methionine in which a formyl group has been added to the amino group. It is specifically used for initiation of protein synthesis from bacterial and organellar genes, and may be removed post-translationally. fMet plays a crucial part in the protein synthesis of bacteria, mitochondria and chloroplasts. It is not used in cytosolic protein synthesis of eukaryotes, where eukaryotic nuclear genes are translated. It is also not used by Archaea. In the human body, fMet is recognized by the immune system as foreign material, or as an alarm signal released by damaged cells, and stimulates the body to fight against potential infection. Function in protein synthesis fMet is a starting residue in the synthesis of proteins in bacteria, and, consequently, is located at the ''N''-terminus of the growing polypeptide. fMet is delivered to the ribosome (30S) - mRNA complex by a specialized tRNA (tRNAfMet) w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formylation
In biochemistry, the addition of a formyl functional group is termed formylation. A formyl functional group consists of a carbonyl bonded to hydrogen. When attached to an R group, a formyl group is called an aldehyde. Formylation has been identified in several critical biological processes. Methionine was first discovered to be formylated in ''E. coli'' by Marcker and Sanger in 1964 and was later identified to be involved in the initiation of protein synthesis in bacteria and organelles. The formation of ''N''-formylmethionine is catalyzed by the enzyme methionyl-tRNA transformylase. Additionally, two formylation reactions occur in the de novo biosynthesis of purines. These reactions are catalyzed by the enzymes glycinamide ribonucleotide (GAR) transformylase and 5-aminoimidazole-4-carboxyamide ribotide (AICAR) transformylase. More recently, formylation has been discovered to be a histone modification, which may modulate gene expression. General formylation reaction Formyla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription (genetics)
Transcription is the process of copying a segment of DNA into RNA. The segments of DNA transcribed into RNA molecules that can encode proteins are said to produce messenger RNA (mRNA). Other segments of DNA are copied into RNA molecules called non-coding RNAs (ncRNAs). mRNA comprises only 1–3% of total RNA samples. Less than 2% of the human genome can be transcribed into mRNA ( Human genome#Coding vs. noncoding DNA), while at least 80% of mammalian genomic DNA can be actively transcribed (in one or more types of cells), with the majority of this 80% considered to be ncRNA. Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. Transcription proceeds in the following general steps: # RNA polymerase, together with one or more general transcription factors, binds to promoter DNA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phagocyte
Phagocytes are cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells. Their name comes from the Greek ', "to eat" or "devour", and "-cyte", the suffix in biology denoting "cell", from the Greek ''kutos'', "hollow vessel". They are essential for fighting infections and for subsequent immunity. Phagocytes are important throughout the animal kingdom and are highly developed within vertebrates. One litre of human blood contains about six billion phagocytes. They were discovered in 1882 by Ilya Ilyich Mechnikov while he was studying starfish larvae.Ilya Mechnikov retrieved on November 28, 2008. Fro ''Physiology or Medicine 1901–1921'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryote
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacteria and Archaea (both prokaryotes) make up the other two domains. The eukaryotes are usually now regarded as having emerged in the Archaea or as a sister of the Asgard archaea. This implies that there are only two domains of life, Bacteria and Archaea, with eukaryotes incorporated among archaea. Eukaryotes represent a small minority of the number of organisms, but, due to their generally much larger size, their collective global biomass is estimated to be about equal to that of prokaryotes. Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the Proterozoic eon, likely as flagellated phagotrophs. Their name comes from the Greek εὖ (''eu'', "well" or "good") and κάρυον (''karyon'', "nut" or "kernel"). Euka ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Innate Immune System
The innate, or nonspecific, immune system is one of the two main immunity strategies (the other being the adaptive immune system) in vertebrates. The innate immune system is an older evolutionary defense strategy, relatively speaking, and is the dominant immune system response found in plants, fungi, insects, and primitive multicellular organisms (see Beyond vertebrates).. The major functions of the innate immune system are to: * recruit immune cells to infection sites by producing chemical factors, including chemical mediators called cytokines * activate the complement cascade to identify bacteria, activate cells, and promote clearance of antibody complexes or dead cells * identify and remove foreign substances present in organs, tissues, blood and lymph, by specialized white blood cells * activate the adaptive immune system through antigen presentation * act as a physical and chemical barrier to infectious agents; via physical measures such as skin and chemical measures such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%–6% by weight) in water for consumer use, and in higher concentrations for industrial use. Concentrated hydrogen peroxide, or " high-test peroxide", decomposes explosively when heated and has been used as a propellant in rocketry. Hydrogen peroxide is a reactive oxygen species and the simplest peroxide, a compound having an oxygen–oxygen single bond. It decomposes slowly when exposed to light, and rapidly in the presence of organic or reactive compounds. It is typically stored with a stabilizer in a weakly acidic solution in a dark bottle to block light. Hydrogen peroxide is found in biological systems including the human body. Enzymes that use or decompose hydrogen peroxide are classified as peroxidases. Properties The boiling poi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superoxide
In chemistry, a superoxide is a compound that contains the superoxide ion, which has the chemical formula . The systematic name of the anion is dioxide(1−). The reactive oxygen ion superoxide is particularly important as the product of the one-electron reduction of dioxygen , which occurs widely in nature. Molecular oxygen (dioxygen) is a diradical containing two unpaired electrons, and superoxide results from the addition of an electron which fills one of the two degenerate molecular orbitals, leaving a charged ionic species with a single unpaired electron and a net negative charge of −1. Both dioxygen and the superoxide anion are free radicals that exhibit paramagnetism. Superoxide was historically also known as "hyperoxide". Salts Superoxide forms salts with alkali metals and alkaline earth metals. The salts caesium superoxide (), rubidium superoxide (), potassium superoxide (), and sodium superoxide () are prepared by the reaction of with the respective alkali me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactive Oxygen Species
In chemistry, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (). Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen. The reduction of molecular oxygen () produces superoxide (), which is the precursor to most other reactive oxygen species: :O2 + e^- -> \ ^\bullet O2- Dismutation of superoxide produces hydrogen peroxide (): :2 H+ + \ ^\bullet O2^- + \ ^\bullet O2^- -> H2O2 + O2 Hydrogen peroxide in turn may be partially reduced, thus forming hydroxide ions and hydroxyl radicals (), or fully reduced to water: :H2O2 + e^- -> HO^- + \ ^\bullet OH :2 H+ + 2 e- + H2O2 -> 2 H2O In a biological context, ROS are byproducts of the normal metabolism of oxygen. ROS have roles in cell signaling and homeostasis. ROS are intrinsic to cellular functioning, and are present at low and stationary levels in normal cells. In plants, ROS are involved in metabolic processes related to photoprotection and toleran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
