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AminocoumarinAminocoumarin is a class of antibiotics which act by an inhibition of the DNA Gyrase enzyme involved in the cell division in bacteria. They are derived from Streptomyces species, whose most well-known representative Streptomyces coelicolor was completely sequenced in 2002.[1] The Aminocoumarin antibiotics include
Additional recommended knowledge
StructureThe core of aminocoumarin antibiotics is made up of a 3-Amino-4,7-dihydroxycumarin ring, which is linked e.g. with a sugar in 7-Position and a benzoic acid derivative in 3-Position. Clorobiocin is a natural antibiotic isolated from several Streptomyces strains and differs from novobiocin in that the methyl group at the 8 position in the coumarin ring of novobiocin is replaced by a chlorine atom, and the carbamoyl at the 3' position of the noviose sugar is substituted by a 5-methyl-2-pyrrolylcarbonyl group.[2] Mechanism of actionThe Aminocoumarin antibiotics are known inhibitors of DNA gyrase. Antibiotics of the aminocoumarin family exert their therapeutic activity by binding tightly to the B subunit of bacterial DNA gyrase, thereby inhibiting this essential enzyme.[3] They compete with ATP for binding to the B subunit of this enzyme and inhibit the ATP-dependent DNA supercoiling catalysed by gyrase.[4] X-ray crystallography studies have confirmed binding at the ATP-binding site located on the gyrB subunit of DNA gyrase.[2]. Their affinity for gyrase is considerably higher than that of modern fluoroquinolones which also target DNA gyrase but at the gyrA subunit.[5] ResistanceResistance to this class of antibiotics usually results from genetic mutation in the gyrB subunit.[6] Other mechanisms include de novo synthesis of a coumarin-resistant gyrase B subunit by the novobiocin producer S. sphaeroides .[5] Clinical useThe clinical use of these antibiotic class has been restricted due to their low water solubility, low activity against gram-negative bacteria[4] and toxiciy in vivo[7].
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Aminocoumarin". A list of authors is available in Wikipedia. |