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Lantibiotics
Lantibiotics are a class of polycyclic peptide antibiotics that contain the characteristic thioether amino acids lanthionine or methyllanthionine, as well as the Saturated and unsaturated compounds, unsaturated amino acids dehydroalanine, and 2-Aminoisobutyric acid, 2-aminoisobutyric acid. They belong to Ribosomally synthesized and post-translationally modified peptides#Lanthipeptides, ribosomally synthesized and post-translationally modified peptides. Lanthionine is composed of two alanine residues that are crosslinked on their β-carbon atoms by a thioether (monosulfide) linkage. Lantibiotics are produced by a large number of Gram-positive bacteria such as ''Streptococcus'' and ''Streptomyces'' to attack other Gram-positive bacteria, and as such, they are considered a member of the bacteriocins. Bacteriocins are classified according to their extent of posttranslational modification. The lantibiotics are a class of more extensively modified bacteriocins, also called Class I bac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nisin
Nisin is a polycyclic antibacterial peptide produced by the bacterium ''Lactococcus lactis'' that is used as a food preservative. It has 34 amino acid residues, including the uncommon amino acids lanthionine (Lan), methyllanthionine (MeLan), didehydroalanine (Dha), and didehydroaminobutyric acid (Dhb). These unusual amino acids are introduced by posttranslational modification of the precursor peptide. In these reactions a ribosome, ribosomally synthesized 57-mer is converted to the final peptide. The unsaturated amino acids originate from serine and threonine, and the enzyme-catalysed addition of cysteine residues to the didehydro amino acids result in the multiple (5) thioether bridges. Subtilin and epidermin are related to nisin. All are members of a class of molecules known as lantibiotics. In the food industry, nisin is obtained from the culturing of ''L. lactis'' on natural substrates, such as dextrose, and it is not chemically synthesized. It was originally isolated in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antibiotic Resistance
Antimicrobial resistance (AMR or AR) occurs when microbes evolve mechanisms that protect them from antimicrobials, which are drugs used to treat infections. This resistance affects all classes of microbes, including bacteria (antibiotic resistance), viruses (antiviral resistance), parasites (antiparasitic resistance), and fungi (antifungal resistance). Together, these adaptations fall under the AMR umbrella, posing significant challenges to healthcare worldwide. Misuse and improper management of antimicrobials are primary drivers of this resistance, though it can also occur naturally through genetic mutations and the spread of resistant genes. Antibiotic resistance, a significant AMR subset, enables bacteria to survive antibiotic treatment, complicating infection management and treatment options. Resistance arises through spontaneous mutation, horizontal gene transfer, and increased selective pressure from antibiotic overuse, both in medicine and agriculture, which accelerat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribosomally Synthesized And Post-translationally Modified Peptides
Ribosomally synthesized and post-translationally modified peptides (RiPPs), also known as ribosomal natural products, are a diverse class of natural products of ribosomal origin. Consisting of more than 20 sub-classes, RiPPs are produced by a variety of organisms, including prokaryotes, eukaryotes, and archaea, and they possess a wide range of biological activity, biological functions. As a consequence of the falling cost of genome sequencing and the accompanying rise in available genomic data, scientific interest in RiPPs has increased in the last few decades. Because the chemical structures of RiPPs are more closely predictable from genomic data than are other natural products (e.g. alkaloids, terpenoids), their presence in sequenced organisms can, in theory, be identified rapidly. This makes RiPPs an attractive target of modern natural product discovery efforts. Definition RiPPs consist of any peptides (i.e. molecular weight below 10 kDa) that are ribosomally-produced and unde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipid II
Lipid II is a precursor molecule in the synthesis of the cell wall of bacteria. It is a peptidoglycan, which is amphipathic and named for its bactoprenol hydrocarbon chain, which acts as a lipid anchor, embedding itself in the bacterial cell membrane. Lipid II must translocate across the cell membrane to deliver and incorporate its disaccharide-pentapeptide "building block" into the peptidoglycan mesh. Lipid II is the target of several antibiotics. A number of analogous compounds are produced via a similar pathway in some bacteria, giving rise to cell wall modifications. See EC 2.4.1.227 for more information. Synthesis In peptidoglycan biosynthetic pathway Lipid II is the final intermediate in peptidoglycan synthesis. It is formed when the MurG transferase catalyzes addition of ''N''-acetylglucosamine (GlcNAc) to Lipid I, resulting in a complete disaccharide-pentapeptide monomer with a bactoprenol-pyrophosphate anchor. This occurs on the inside of the cytoplasmic membrane, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclic Peptide
Cyclic peptides are polypeptide chains which contain a circular sequence of bonds. This can be through a connection between the amino and carboxyl ends of the peptide, for example in cyclosporin; a connection between the amino end and a side chain, for example in bacitracin; the carboxyl end and a side chain, for example in colistin; or two side chains or more complicated arrangements, for example in alpha-amanitin. Many cyclic peptides have been discovered in nature and many others have been synthesized in the laboratory. Their length ranges from just two amino acid residues to hundreds. In nature they are frequently antimicrobial or toxic; in medicine they have various applications, for example as antibiotics and immunosuppressive agents. Thin-layer chromatography, Thin-Layer Chromatography (TLC) is a convenient method to detect cyclic peptides in crude extract from bio-mass. Classification Cyclic peptides can be classified according to the types of bonds that comprise the ring ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Class II Bacteriocin
Class II bacteriocins are a class of small peptides that inhibit the growth of various bacteria. Many Gram-positive bacteria produce ribosomally synthesized antimicrobial peptides, termed bacteriocins. Bacteriocins for which disulfide bonds are the only modification to the peptide are Class II bacteriocins. Class IIa One important and well studied class of bacteriocins is the class IIa or pediocin-like bacteriocins produced by lactic acid bacteria. All class IIa bacteriocins are produced by food-associated strains, isolated from a variety of food products of industrial and natural origins, including meat products, dairy products and vegetables. Class IIa bacteriocins are all cationic, display anti-''Listeria'' activity, and kill target cells by permeabilizing the cell membrane. Class IIa bacteriocins contain between 37 and 48 residues. Based on their primary structures, the peptide chains of class IIa bacteriocins may be divided roughly into two regions: a hydrophilic, cationi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biosynthesis
Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-Catalysis, catalyzed processes where chemical substances absorbed as nutrients (or previously converted through biosynthesis) serve as enzyme substrate (chemistry), substrates, with conversion by the living organism either into simpler or more complex Product (chemistry), products. Examples of biosynthetic pathways include those for the production of amino acids, lipid membrane components, and nucleotides, but also for the production of all classes of biological macromolecules, and of acetyl-coenzyme A, adenosine triphosphate, nicotinamide adenine dinucleotide and other key intermediate and transactional molecules needed for metabolism. Thus, in biosynthesis, any of an array of Chemical compound, compounds, from simple to complex, are converted into other compounds, and so it includes both the catabolism and anabolism (building up and breaking down) of comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antimicrobial
An antimicrobial is an agent that kills microorganisms (microbicide) or stops their growth (bacteriostatic agent). Antimicrobial medicines can be grouped according to the microorganisms they are used to treat. For example, antibiotics are used against bacteria, and antifungals are used against fungi. They can also be classified according to their function. Antimicrobial medicines to treat infection are known as antimicrobial chemotherapy, while antimicrobial drugs are used to prevent infection, which known as antibiotic prophylaxis, antimicrobial prophylaxis. The main classes of antimicrobial agents are disinfectants (non-selective agents, such as bleach), which kill a wide range of microbes on surfaces to prevent the spread of illness, antiseptics which are applied to living tissue and help reduce infection during surgery, and antibiotics which destroy microorganisms within the body. The term ''antibiotic'' originally described only those formulations derived from living microorga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Membrane
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of a cell, being selectively permeable to ions and organic mole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphoethanolamine
Phosphorylethanolamine or phosphoethanolamine is an ethanolamine derivative that is used to construct two different categories of phospholipids. One category termed a glycerophospholipid and the other a sphingomyelin, or more specifically within the sphingomyelin class, a sphingophospholipid. Phosphorylethanolamine is a polyprotic acid with two pKa values at 5.61 and 10.39. Phosphorylethanolamine has been falsely promoted as a cancer treatment. Effectiveness As a potential drug, phosphorylethanolamine has undergone human clinical trials. These were halted when no evidence of benefit was found. Edzard Ernst has called phosphorylethanolamine "the most peculiar case of Brazilian quackery". Legality There has been ongoing controversy and litigation in Brazil with regard to its use as a cancer treatment without approval by the National Health Surveillance Agency. For years, Gilberto Chierice, a Chemistry Professor at the São Carlos campus of the University of São Paulo, used resou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
