Gyrase enzyme

Difflam benzydamine. diflorasone flumethasone. diflorasone diacetate flumethasone. difloxacin [inn] (difloxacin hydrochloride [usan]) is a quinolinecarboxylic acid ANTIBACTERIAL (a DNA gyrase enzyme inhibitor). 

Two classes of antimicrobial gyrase inhibitors i.e., 4-quinolones like oxolinic acid (87), and coumarins (novobiocin and coumermycin Al) have been used to represent the different aspects of gyrase and topoisomerase reaction. Coumarins are inhibitors of the ATP hydrolysis and DNA supercoiling reactions catalyzed by DNA gyrase [286]. They block ATP hydrolysis at the Gyr B subunit [287]. Organisms like Borrelia burgdorferi, have gyrase enzyme resistant to nalidixic acid or oxolinic acid (87) type inhibitors, but show a distinct sensitivity to coumarin antibiotics like coumermycin. This phenomenon opens a prospect of... 

Gyrase is another term for bacterial topoisomerase II. The enzyme consists of two A and two B subunits and is responsible for the negative supercoiling of the bacterial DNA. Negative supercoiling makes the bacterial DNA more compact and also more readily accessible to enzymes that cause duplication and transcription of the DNA to RNA. 

The enzymes gyrase and topoisomerase IV can be protected from fluoroquinolone inhibition by a small protein belonging to the pentapeptide-repeat family of... 

The fluoroquinolones exert their bactericidal (bacteria-destroying) effect by interfering with an enzyme (DNA gyrase) needed by bacteria for the synthesis of DNA. 

The amplification of genetic information, i.e., the replication of parent DNA molecules, is achieved by means of an entire set of enzymes. The major players are a DNA-gyrase for unwinding of the double helix, proteins to separate the two antiparallel DNA strands at the replicational junction, single-stranded binding proteins (SSB) that prevent the... 

As described in section 4.1, the DNA double helix must unwind to allow access ofthe polymerase enzymes to produce two new strands ofDNA. This is facilitated by DNA gyrase, the target of the quinolones. Some agents interfere with the unwinding of the chromosome by physical obstruction. These include the acridine dyes, of which the topical antiseptic proflavine is the most familiar, and the antimalarial acridine, mepacrine. They prevent strand separation by insertion (intercalation) between base pairs from each strand, but exhibit very poor selective toxicity. 

Fig. 19.3 Flow chart of 3D structure-based biased needle screening as applied to the bacterial enzyme, gyrase.

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