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Bactoprenol
Bactoprenol also known as dolichol-11 and (isomerically vaguely) C55-isoprenyl alcohol (C55-OH) is a lipid first identified in certain species of lactobacili. It is a hydrophobic alcohol that plays a key role in the growth of cell walls (peptidoglycan) in Gram-positive bacteria. The double bonds all have the Z configuration except for the three ω-terminal ones, which are biosynthetically derived from (E,E)- farnesyl diphosphate. Occurrence Bactoprenol is a lipid synthesized from mevalonic acid and is the most abundant lipid found in certain species of lactobacilli. Bactoprenol is found in both mesosomal and plasma membranes. Mesosomal and plasma bactoprenol are synthesized independently from each other. Function Bactoprenol is thought to play a key role in the formation of cell walls in gram-positive bacteria by cycling peptidoglycan monomers through the plasma membrane and inserting these monomers at points of growth in the bacterial cell wall. Antibiotic signifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peptidoglycan
Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall (murein sacculus) characteristic of most bacteria (domain ''Bacteria''). The sugar component consists of alternating residues of β-(1,4) linked ''N''-acetylglucosamine (NAG) and ''N''-acetylmuramic acid (NAM). Attached to the ''N''-acetylmuramic acid is a oligopeptide chain made of three to five amino acids. The peptide chain can be cross-linked to the peptide chain of another strand forming the 3D mesh-like layer. Peptidoglycan serves a structural role in the bacterial cell wall, giving structural strength, as well as counteracting the osmotic pressure of the cytoplasm. This repetitive linking results in a dense peptidoglycan layer which is critical for maintaining cell form and withstanding high osmotic pressures, and it is regularly replaced by peptidoglycan production. Pep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipid
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries, and in nanotechnology. Lipids may be broadly defined as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, multilamellar/unilamellar liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks": ketoacyl and isoprene groups. Using this approach, lipids may be divided into eight categories: fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, and polyketides (derived from condensati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactobacilli
The ''Lactobacillaceae'' are a family of lactic acid bacteria. It is the only family in the lactic acid bacteria which includes homofermentative and heterofermentative organisms; in the ''Lactobacillaceae,'' the pathway used for hexose fermentation is a genus-specific trait. ''Lactobacillaceae'' include the homofermentative lactobacilli ''Lactobacillus'', ''Holzapfelia'', ''Amylolactobacillus'', ''Bombilactobacillus'', ''Companilactobacillus'', ''Lapidilactobacillus'', ''Agrilactobacillus'', ''Schleiferilactobacillus'', ''Loigolactobacillus'', ''Lacticaseibacillus'', ''Latilactobacillus'', ''Dellaglioa'', ''Liquorilactobacillus'', ''Ligilactobacillus'', and ''Lactiplantibacillus''; the heterofermentative lactobacilli ''Furfurilactobacillus'', ''Paucilactobacillus'', ''Limosilactobacillus'', ''Fructilactobacillus'', ''Acetilactobacillus'', ''Apilactobacillus'', ''Levilactobacillus'', ''Secundilactobacillus'', and ''Lentilactobacillus,'' which were previously classified in the genus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lantibiotics
Lantibiotics are a class of polycyclic peptide antibiotics that contain the characteristic thioether amino acids lanthionine or methyllanthionine, as well as the unsaturated amino acids dehydroalanine, and 2-aminoisobutyric acid. They belong to 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 bacteriocins. (Bacteriocins for which disulfide bonds are the only modification to the peptide are Class II bacteriocins.) Lantibiotics are w ... [...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 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 milk or dextrose, and it is not chemically synthesized. It was originally isolated in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friulimicin
Friulimicin B is a lipopeptide antibiotic produced by ''Actinoplanes friuliensis ''Actinoplanes friuliensis'' is a species of bacteria that produces lipopeptide antibiotics with peptidoglycan Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-li ...''. It includes the unusual amino acid methylaspartate. References {{reflist Antibiotics Lipopeptides Cyclic peptides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of such infections. They may either kill or inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity. Antibiotics are not effective against viruses such as the common cold or influenza; drugs which inhibit viruses are termed antiviral drugs or antivirals rather than antibiotics. Sometimes, the term ''antibiotic''—literally "opposing life", from the Greek roots ἀντι ''anti'', "against" and βίος ''bios'', "life"—is broadly used to refer to any substance used against microbes, but in the usual medical usage, antibiotics (such as penicillin) are those produced naturally (by one microorganism fighting another), whereas non-antibiotic antibacterials (such as sulfonamides and antiseptics) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasma Membranes
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells 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 cells and organelles, being selectively permeable to ions a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesosome
Mesosomes or chondrioids are folded invaginations in the plasma membrane of bacteria that are produced by the chemical fixation techniques used to prepare samples for electron microscopy. Although several functions were proposed for these structures in the 1960s, they were recognized as artifacts by the late 1970s and are no longer considered to be part of the normal structure of bacterial cells. These extensions are in the form of vesicles, tubules and lamellae. Initial observations These structures are invaginations of the plasma membrane observed in gram-positive bacteria that have been chemically fixed to prepare them for electron microscopy. They were first observed in 1953 by George B. Chapman and James Hillier, who referred to them as "peripheral bodies." They were termed "mesosomes" by Fitz-James in 1960. Initially, it was thought that mesosomes might play a role in several cellular processes, such as cell wall formation during cell division, chromosome replication, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mevalonic Acid
Mevalonic acid (MVA) is a key organic compound in biochemistry; the name is a contraction of dihydroxymethylvalerolactone. The carboxylate anion of mevalonic acid, which is the predominant form in biological environments, is known as ''mevalonate'' and is of major pharmaceutical importance. Drugs like statins (which lower levels of cholesterol) stop the production of mevalonate by inhibiting HMG-CoA reductase. Chemistry Mevalonic acid is very soluble in water and polar organic solvents. It exists in equilibrium with its lactone form, called mevalonolactone, that is formed by internal condensation of its terminal alcohol and carboxylic acid functional groups. Biology Mevalonic acid is a precursor in the biosynthetic pathway known as the mevalonate pathway that produces terpenes and steroids. Mevalonic acid is the primary precursor of isopentenyl pyrophosphate (IPP), that is in turn the basis for all terpenoids. Mevalonic acid is chiral and the (3''R'')-enantiomer In chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactobacillus
''Lactobacillus'' is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically diverse species; a taxonomic revision of the genus assigned lactobacilli to 25 genera (see below). ''Lactobacillus'' species constitute a significant component of the human and animal microbiota at a number of body sites, such as the digestive system, and the female genital system. In women of European ancestry, ''Lactobacillus'' species are normally a major part of the vaginal microbiota. ''Lactobacillus'' forms biofilms in the vaginal and gut microbiota, allowing them to persist during harsh environmental conditions and maintain ample populations. ''Lactobacillus'' exhibits a mutualistic relationship with the human body, as it protects the host against potential invasions by pathogens, and in turn, the host provides a source of nutrien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
