1.
Bacteria
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Bacteria constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods, Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only half of the bacterial phyla have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology, There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are approximately 5×1030 bacteria on Earth, forming a biomass which exceeds that of all plants, Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of bodies and bacteria are responsible for the putrefaction stage in this process. In March 2013, data reported by researchers in October 2012, was published and it was suggested that bacteria thrive in the Mariana Trench, which with a depth of up to 11 kilometres is the deepest known part of the oceans. Other researchers reported related studies that microbes thrive inside rocks up to 580 metres below the sea floor under 2.6 kilometres of ocean off the coast of the northwestern United States. According to one of the researchers, You can find microbes everywhere—theyre extremely adaptable to conditions, the vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial particularly in the gut flora. However several species of bacteria are pathogenic and cause diseases, including cholera, syphilis, anthrax, leprosy. The most common fatal diseases are respiratory infections, with tuberculosis alone killing about 2 million people per year. In developed countries, antibiotics are used to treat infections and are also used in farming, making antibiotic resistance a growing problem. Once regarded as constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and these evolutionary domains are called Bacteria and Archaea. The ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, for about 3 billion years, most organisms were microscopic, and bacteria and archaea were the dominant forms of life. In 2008, fossils of macroorganisms were discovered and named as the Francevillian biota, however, gene sequences can be used to reconstruct the bacterial phylogeny, and these studies indicate that bacteria diverged first from the archaeal/eukaryotic lineage. Bacteria were also involved in the second great evolutionary divergence, that of the archaea, here, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves possibly related to the Archaea
2.
Antimicrobial resistance
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Antimicrobial resistance is the ability of a microbe to resist the effects of medication previously used to treat them. This broader term also covers antibiotic resistance, which applies to bacteria, resistance arises through one of three ways, natural resistance in certain types of bacteria, genetic mutation, or by one species acquiring resistance from another. Resistance can appear spontaneously because of mutations, or more commonly following gradual buildup over time. Resistant microbes are increasingly difficult to treat, requiring alternative medications or higher doses, microbes resistant to multiple antimicrobials are called multidrug resistant, or sometimes superbugs. Antimicrobial resistance is on the rise with millions of deaths every year, Antibiotics should only be used when needed as prescribed by health professionals. The prescriber should closely adhere to the five rights of administration, the right patient, the right drug, the right dose, the right route. Narrow-spectrum antibiotics are preferred over broad-spectrum antibiotics when possible, as effectively and accurately targeting specific organisms is less likely to cause resistance, cultures should be taken before treatment when indicated and treatment potentially changed based on the susceptibility report. For people who take these medications at home, education about proper use is essential, rising drug resistance is caused mainly by improper use of antimicrobials in humans as well as in animals, and spread of resistant strains between the two. Antibiotics increase selective pressure in bacterial populations, causing vulnerable bacteria to die, with resistance to antibiotics becoming more common there is greater need for alternative treatments. Calls for new antibiotic therapies have been issued, but new development is becoming rarer. Antibiotic resistance—when bacteria change so antibiotics no longer work in people who need them to treat infections—is now a threat to public health. Increasing public calls for collective action to address the threat include proposals for international treaties on antimicrobial resistance. Worldwide antibiotic resistance is not fully mapped, but poorer countries with weak healthcare systems are more affected, the WHO defines antimicrobial resistance as a microorganisms resistance to an antimicrobial drug that was once able to treat an infection by that microorganism. A person cannot become resistant to antibiotics, resistance is a property of the microbe, not a person or other organism infected by a microbe. Bacteria with resistance to antibiotics predate medical use of antibiotics by humans, however and this may result in emergence of resistance in any remaining bacteria. Antibiotic use in feed at low doses for growth promotion is an accepted practice in many industrialized countries and is known to lead to increased levels of resistance. It is uncertain whether antibacterials in soaps and other products contribute to antibiotic resistance, increasing bacterial resistance is linked with the volume of antibiotic prescribed, as well as missing doses when taking antibiotics. Up to half of antibiotics used in humans are unnecessary and inappropriate, a single regimen of antibiotics even in compliant individuals leads to a greater risk of resistant organisms to that antibiotic in the person for a month to possibly a year
3.
Grignard reaction
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The Grignard reaction is an organometallic chemical reaction in which alkyl, vinyl, or aryl-magnesium halides add to a carbonyl group in an aldehyde or ketone. This reaction is an important tool for the formation of carbon–carbon bonds, the reaction of an organic halide with magnesium is not a Grignard reaction, but provides a Grignard reagent. Grignard reagents are similar to organolithium reagents because both are strong nucleophiles that can form new carbon–carbon bonds, the nucleophilicity increases if the alkyl substituent is replaced by an amido group. These amido magnesium halides are called Hauser bases, the Grignard reagent functions as a nucleophile, attacking the electrophilic carbon atom that is present within the polar bond of a carbonyl group. The addition of the Grignard reagent to the carbonyl typically proceeds through a ring transition state. However, with hindered Grignard reagents, the reaction may proceed by single-electron transfer, similar pathways are assumed for other reactions of Grignard reagents, e. g. in the formation of carbon–phosphorus, carbon–tin, carbon–silicon, carbon–boron and other carbon–heteroatom bonds. Grignard reagents form via the reaction of an alkyl or alkyl halide with magnesium metal, the reaction is conducted by adding the organic halide to a suspension of magnesium in an etherial solvent, which provides ligands required to stabilize the organomagnesium compound. Empirical evidence suggests that the reaction takes place on the surface of the metal, the reaction proceeds through single electron transfer, In the Grignard formation reaction, radicals may be converted into carbanions through a second electron transfer. R−X + Mg → R−X•− + Mg•+ R−X•− → R• + X− R• + Mg•+ → RMg+ RMg+ + X− → RMgX A limitation of Grignard reagents is that they do not readily react with alkyl halides via an SN2 mechanism. In reactions involving Grignard reagents, it is important to water and air. Since most Grignard reactions are conducted in diethyl ether or tetrahydrofuran. Small-scale or quantitative preparations should be conducted under nitrogen or argon atmospheres, although the reagents still need to be dry, ultrasound can allow Grignard reagents to form in wet solvents by activating the magnesium such that it consumes the water. As is common for reactions involving solids and solution, initiation follows a period during which reactive magnesium becomes exposed to the organic reagents. After this induction period, the reactions can be highly exothermic, Alkyl and aryl bromides and iodides are common, with chlorides being seen as well. However, fluorides are generally unreactive, except with specially activated magnesium, typical Grignard reactions involve the use of magnesium ribbon. All magnesium is coated with a layer of magnesium oxide. Specially activated magnesium, such as Rieke magnesium, circumvents this problem, the oxide layer can also be broken up using ultrasound, or by adding a few drops of iodine or 1, 2-Diiodoethane. Most Grignard reactions are conducted in solvents, especially diethyl ether
4.
Stem cell
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Stem cells are undifferentiated biological cells that can differentiate into specialized cells and can divide to produce more stem cells. They are found in multicellular organisms, in mammals, there are two broad types of stem cells, embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and adult stem cells, which are found in various tissues. In adult organisms, stem cells and progenitor cells act as a system for the body. There are three known accessible sources of adult stem cells in humans, Bone marrow, which requires extraction by harvesting. Adipose tissue, which requires extraction by liposuction, Stem cells can also be taken from umbilical cord blood just after birth. Of all stem cell types, autologous harvesting involves the least risk, by definition, autologous cells are obtained from ones own body, just as one may bank his or her own blood for elective surgical procedures. Adult stem cells are used in various medical therapies. Stem cells can now be artificially grown and transformed into specialized cell types with characteristics consistent with cells of tissues such as muscles or nerves. Embryonic cell lines and autologous stem cells generated through somatic cell nuclear transfer or dedifferentiation have also been proposed as promising candidates for future therapies. Research into stem cells grew out of findings by Ernest A. McCulloch, till at the University of Toronto in the 1960s. The classical definition of a cell requires that it possess two properties, Self-renewal, the ability to go through numerous cycles of cell division while maintaining the undifferentiated state. Potency, the capacity to differentiate into specialized cell types, apart from this it is said that stem cell function is regulated in a feed back mechanism. Stochastic differentiation, when one cell develops into two differentiated daughter cells, another stem cell undergoes mitosis and produces two stem cells identical to the original. Potency specifies the differentiation potential of the stem cell, totipotent stem cells can differentiate into embryonic and extraembryonic cell types. Such cells can construct a complete, viable organism and these cells are produced from the fusion of an egg and sperm cell. Cells produced by the first few divisions of the egg are also totipotent. Pluripotent stem cells are the descendants of totipotent cells and can differentiate into all cells. Multipotent stem cells can differentiate into a number of cell types, oligopotent stem cells can differentiate into only a few cell types, such as lymphoid or myeloid stem cells
5.
Hermann Staudinger
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Hermann Staudinger was a German organic chemist who demonstrated the existence of macromolecules, which he characterized as polymers. For this work he received the 1953 Nobel Prize in Chemistry and he is also known for his discovery of ketenes and of the Staudinger reaction. Hermann Staudinger was born in 1881 in Worms, after receiving his Ph. D. from the University of Halle in 1903, Staudinger took a position at the University of Strasbourg. It was here that he discovered the ketenes, a family of molecules characterized by the general depicted in Figure 1. Ketenes would prove an important intermediate for the production of yet-to-be-discovered antibiotics such as penicillin and amoxicillin. In 1907, Staudinger began an assistant professorship at the Technical University of Karlsruhe, here, he successfully isolated a number of useful organic compounds as more completely reviewed by Rolf Mülhaupt. In 1912, Staudinger took on a new position at the Swiss Federal Institute of Technology in Zurich, one of his earliest discoveries came in 1919, when he and colleague Meyer reported that azides react with triphenylphosphine to form phosphazide. This reaction – commonly referred to as the Staudinger reaction – produces a high phosphazide yield. While at Karlsruhe and later, Zurich, Staudinger began research in the chemistry of rubber, for very high molecular weights had been measured by the physical methods of Raoult. In other words, polymers are like chains of paper clips, at first the majority of Staudinger’s colleagues refused to accept the possibility that small molecules could link together covalently to form high-molecular weight compounds. As Mülhaupt aptly notes, this is due in part to the fact that molecular structure, in 1926 he was appointed lecturer of chemistry at the University of Freiburg at Freiburg in Breisgau, where he spent the rest of his career. In 1927, he married the Latvian botanist, Magda Voita (also shown as, further evidence to support his polymer hypothesis emerged in the 1930s. High molecular weights of polymers were confirmed by membrane osmometry, the X-ray diffraction studies of polymers by Herman Mark provided direct evidence for long chains of repeating molecular units. And the synthetic work led by Carothers demonstrated that such as nylon. His theory opened up the subject to development, and helped place polymer science on a sound basis. Staudinger’s groundbreaking elucidation of the nature of the high-molecular weight compounds he termed Makromoleküle paved the way for the birth of the field of polymer chemistry, Staudinger himself saw the potential for this science long before it was fully realized. e. Staudinger founded the first polymer chemistry journal in 1940, and in 1953 received the Nobel Prize in Chemistry for “his discoveries in the field of macromolecular chemistry. ”In 1999, heidegger and Nazism, denounced or demoted non-Nazis Polymer science Helmut Ringsdorf. Hermann Staudinger and the Future of Polymer Research Jubilees – Beloved Occasions for Cultural Piety, ogilvie, Marilyn Bailey, Harvey, Joy Dorothy
6.
Beta-lactamase
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Beta-lactamase provides antibiotic resistance by breaking the antibiotics structure. These antibiotics all have an element in their molecular structure. Through hydrolysis, the lactamase enzyme breaks the β-lactam ring open, beta-lactam antibiotics are typically used to treat a broad spectrum of Gram-positive and Gram-negative bacteria. Beta-lactamases produced by Gram-negative organisms are usually secreted, especially when antibiotics are present in the environment, the structure of a Streptomyces β-lactamase is given by 1BSG. Penicillinase is a type of β-lactamase, showing specificity for penicillins. Molecular weights of the various penicillinases tend to cluster near 50 kiloDaltons, penicillinase-resistant beta-lactams such as methicillin were developed, but there is now widespread resistance to even these. Additionally, many class A TEM β-lactamases are inhibited by β-lactamase inhibitor protein, because of the increasing number of TEM- and SHV-derived β-lactamases, they were divided into two subclasses, 2a and 2b. GROUP 2a PENICILLINASE, Molecular Class A The 2a subgroup contains just penicillinases, GROUP 2b BROAD-SPECTRUM, Molecular Class A 2b Opposite to 2a, 2b are broad-spectrum β-lactamases, meaning that they are capable of inactivating penicillins and cephalosporins at the same rate. GROUP 2c CARBENICILLINASE, Molecular Class A Latersubgroup 2c was segregated from group 2 because these enzymes inactivate carbenicillin more than benzylpenicillin and these enzymes are able to inactivate the oxazolylpenicillins like oxacillin, cloxacillin, dicloxacillin. The enzymes belong to the molecular class D not molecular class A. Metallo B-lactamases are able to hydrolyse penicillins, cephalosporins and this group has been omitted from the current scheme, as when it was described originally it included enzymes not classifiable into other groups. The molecular classification of β-lactamases is based on the nucleotide and amino acid sequences in these enzymes, to date, four classes are recognised, correlating with the functional classification. Among Gram-negative bacteria, the emergence of resistance to expanded-spectrum cephalosporins has been a major concern and it appeared initially in a limited number of bacterial species that could mutate to hyperproduce their chromosomal class C β-lactamase. A few years later, resistance appeared in bacterial species not naturally producing AmpC enzymes due to the production of TEM- or SHV-type ESBLs, members of the family commonly express plasmid-encoded β-lactamases. Which confer resistance to penicillins but not to expanded-spectrum cephalosporins, in the mid-1980s, a new group of enzymes, the extended-spectrum β-lactamases, was detected. The prevalence of ESBL-producing bacteria have been increasing in acute care hospitals. ESBLs are beta-lactamases that hydrolyze extended-spectrum cephalosporins with a side chain. These cephalosporins include cefotaxime, ceftriaxone, and ceftazidime, as well as the oxyimino-monobactam aztreonam, thus ESBLs confer multi-resistance to these antibiotics and related oxyimino-beta lactams. In typical circumstances, they derive from genes for TEM-1, TEM-2, a broader set of β-lactam antibiotics are susceptible to hydrolysis by these enzymes
7.
Robert Burns Woodward
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Robert Burns Woodward was an American organic chemist. He also worked closely with Roald Hoffmann on theoretical studies of chemical reactions and he was awarded the Nobel Prize in Chemistry in 1965. Woodward was born in Boston, Massachusetts, to Margaret and Arthur Chester Woodward, son of Roxbury, Massachusetts apothecary, when Robert was one year old, his father died in the flu pandemic of 1918. From a very early age, Woodward was attracted to and engaged in study of chemistry while he attended a public primary school. By the time he entered school, he had already managed to perform most of the experiments in Ludwig Gattermanns then widely used textbook of experimental organic chemistry. In 1928, Woodward contacted the Consul-General of the German consulate in Boston, later, in his Cope lecture, he recalled how he had been fascinated when, among these papers, he chanced upon Diels and Alders original communication about the Diels–Alder reaction. Throughout his career, Woodward was to repeatedly and powerfully use and investigate this reaction, in 1933, he entered the Massachusetts Institute of Technology, but neglected his formal studies badly enough to be excluded at the end of the 1934 fall term. MIT readmitted him in the 1935 fall term, and by 1936 he had received the Bachelor of Science degree, only one year later, MIT awarded him the doctorate, when his classmates were still graduating with their bachelors degrees. Woodwards doctoral work involved investigations related to the synthesis of the sex hormone estrone. MIT required that students have research advisors. Woodwards advisors were James Flack Norris and Avery Adrian Morton, although it is not clear whether he took any of their advice. In the 1960s, Woodward was named Donner Professor of Science, in 1944, with his post doctoral researcher, William von Eggers Doering, Woodward reported the synthesis of the alkaloid quinine, used to treat malaria. Nevertheless, it was a landmark for chemical synthesis, Woodwards particular insight in this synthesis was to realise that the German chemist Paul Rabe had converted a precursor of quinine called quinotoxine to quinine in 1905. Hence, a synthesis of quinotoxine would establish a route to synthesizing quinine, when Woodward accomplished this feat, organic synthesis was still largely a matter of trial and error, and nobody thought that such complex structures could actually be constructed. Woodward showed that organic synthesis could be made into a science. This synthesis was the first one in a series of exceedingly complicated, Woodward was perhaps the first synthetic organic chemist who used these ideas as a predictive framework in synthesis. Woodwards style was the inspiration for the work of hundreds of successive synthetic chemists who synthesized medicinally important, during the late 1940s, Woodward synthesized many complex natural products including quinine, cholesterol, cortisone, strychnine, lysergic acid, reserpine, chlorophyll, cephalosporin, and colchicine. Many of Woodwards syntheses were described as spectacular by his colleagues and before he did them, Woodwards syntheses were also described as having an element of art in them, and since then, synthetic chemists have always looked for elegance as well as utility in synthesis
8.
Cell wall
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A cell wall is a structural layer surrounding some types of cells, situated outside the cell membrane. It can be tough, flexible, and sometimes rigid and it provides the cell with both structural support and protection, and also acts as a filtering mechanism. Cell walls are present in most prokaryotes, in algae, plants and fungi, a major function is to act as pressure vessels, preventing over-expansion of the cell when water enters. The composition of cell walls varies between species and may depend on type and developmental stage. The primary cell wall of plants is composed of the polysaccharides cellulose, hemicellulose. Often, other such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae possess walls made of glycoproteins and polysaccharides such as carrageenan, in bacteria, the cell wall is composed of peptidoglycan. The cell walls of archaea have various compositions, and may be formed of glycoprotein S-layers, pseudopeptidoglycan, Fungi possess cell walls made of the glucosamine polymer chitin. Unusually, diatoms have a wall composed of biogenic silica. A plant cell wall was first observed and named by Robert Hooke in 1665, in 1804, Karl Rudolphi and J. H. F. Link proved that cells had independent cell walls, before, it had been thought that cells shared walls and that fluid passed between them this way. The mode of formation of the wall was controversial in the 19th century. Hugo von Mohl advocated the idea that the wall grows by apposition. Carl Nägeli believed that the growth of the wall in thickness, each theory was improved in the following decades, the apposition theory by Eduard Strasburger, and the intussusception theory by Julius Wiesner. In 1930, Ernst Münch coined the term apoplast in order to separate the living symplast from the dead plant region, Cell walls serve similar purposes in those organisms that possess them. They may give cells rigidity and strength, offering protection against mechanical stress, in multicellular organisms, they permit the organism to build and hold a definite shape. Cell walls also limit the entry of large molecules that may be toxic to the cell and they further permit the creation of stable osmotic environments by preventing osmotic lysis and helping to retain water. Their composition, properties, and form may change during the cell cycle, in most cells, the cell wall is flexible, meaning that it will bend rather than holding a fixed shape, but has considerable tensile strength
9.
Aniline
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Aniline is an organic compound with the formula C6H5NH2. Consisting of a group attached to an amino group, aniline is the prototypical aromatic amine. Its main use is in the manufacture of precursors to polyurethane, like most volatile amines, it possesses the odour of rotten fish. It ignites readily, burning with a smoky flame characteristic of aromatic compounds, the amine is nearly planar owing to conjugation of the lone pair with the aryl substituent. The C-N distance is correspondingly shorter, in aniline, the C-N and C-C distances are close to 1.39 Å, indicating the π-bonding between N and C. Industrial aniline production involves two steps, first, benzene is nitrated with a concentrated mixture of nitric acid and sulfuric acid at 50 to 60 °C to yield nitrobenzene. The nitrobenzene is then hydrogenated in the presence of metal catalysts, the reduction of nitrobenzene to aniline was first performed by Nikolay Zinin in 1842 using inorganic sulfide as a reductant. Aniline can alternatively be prepared from ammonia and phenol derived from the cumene process, many analogues of aniline are known where the phenyl group is further substituted. These include toluidines, xylidines, chloroanilines, aminobenzoic acids, nitroanilines and they often are prepared by nitration of the substituted aromatic compounds followed by reduction. For example, this approach is used to convert toluene into toluidines, the chemistry of aniline is rich because the compound has been cheaply available for many years. Below are some classes of its reactions, the oxidation of aniline has been heavily investigated, and can result in reactions localized at nitrogen or more commonly results in the formation of new C-N bonds. In alkaline solution, azobenzene results, whereas arsenic acid produces the violet-coloring matter violaniline, chromic acid converts it into quinone, whereas chlorates, in the presence of certain metallic salts, give aniline black. Hydrochloric acid and potassium chlorate give chloranil, potassium permanganate in neutral solution oxidizes it to nitrobenzene, in alkaline solution to azobenzene, ammonia and oxalic acid, in acid solution to aniline black. Hypochlorous acid gives 4-aminophenol and para-amino diphenylamine, oxidation with persulfate affords a variety of polyanilines compounds. These polymers exhibit rich redox and acid-base properties, like phenols, aniline derivatives are highly susceptible to electrophilic substitution reactions. Its high reactivity reflects that it is an enamine, which enhances the ability of the ring. For example, reaction of aniline with sulfuric acid at 180 °C produces sulfanilic acid, if bromine water is added to aniline, the bromine water is decolourised and a white precipitate of 2,4, 6-tribromophenylamine is formed. The largest scale industrial reaction of aniline involves its alkylation with formaldehyde, an idealized equation is shown,2 C6H5NH2 + CH2O → CH22 + H2O The resulting diamine is the precursor to 4, 4-MDI and related diisocyanates
10.
Antimicrobial peptides
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Antimicrobial peptides, also called host defense peptides are part of the innate immune response found among all classes of life. Fundamental differences exist between prokaryotic and eukaryotic cells that may represent targets for antimicrobial peptides and these peptides are potent, broad spectrum antibiotics which demonstrate potential as novel therapeutic agents. Antimicrobial peptides have been demonstrated to kill Gram negative and Gram positive bacteria, enveloped viruses, fungi, unlike the majority of conventional antibiotics it appears as though antimicrobial peptides may also have the ability to enhance immunity by functioning as immunomodulators. Marine fish sources have high levels of compounds with in vivo testing confirming the efficacy of fish peptides used in food/feed ingredients. Antimicrobial peptides are a unique and diverse group of molecules, which are divided into subgroups on the basis of their amino acid composition, Antimicrobial peptides are generally between 12 and 50 amino acids. These peptides include two or more positively charged residues provided by arginine, lysine or, in environments, histidine. Many of these peptides are unstructured in free solution, and fold into their final configuration upon partitioning into biological membranes and it contains hydrophilic amino acid residues aligned along one side and hydrophobic amino acid residues aligned along the opposite side of a helical molecule. This amphipathicity of the antimicrobial peptides allows them to partition into the lipid bilayer. The ability to associate with membranes is a feature of antimicrobial peptides although membrane permeabilization is not necessary. These peptides have a variety of activities ranging from membrane permeabilization to action on a range of cytoplasmic targets. The modes of action by which antimicrobial peptides kill microbes are varied, some antimicrobial peptides kill both bacteria and fungi, e. g. psoriasin kills E. coli and several filamentous fungi. The cytoplasmic membrane is a frequent target, but peptides may also interfere with DNA and protein synthesis, protein folding, and cell wall synthesis. The initial contact between the peptide and the organism is electrostatic, as most bacterial surfaces are anionic, or hydrophobic. Alternately, they may penetrate into the cell to bind intracellular molecules which are crucial to cell living, however, in many cases, the exact mechanism of killing is not known. One emerging technique for the study of such mechanisms is dual polarisation interferometry, in contrast to many conventional antibiotics these peptides appear to be bactericidal instead of bacteriostatic. In general the antimicrobial activity of peptides is determined by measuring the minimal inhibitory concentration. Animal models indicate that host defence peptides are crucial for both prevention and clearance of infection and it appears as though many peptides initially isolated as and termed antimicrobial peptides have been shown to have more significant alternative functions in vivo. Several methods have used to determine the mechanisms of antimicrobial peptide activity
