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Ciprofloxacin is a fluoroquinolone antibiotic used to treat a number of bacterial infections. This includes bone and joint infections, intra-abdominal infections, certain types of infectious diarrhea, respiratory tract infections, skin infections, typhoid fever, and urinary tract infections, among others. For some infections it is used in addition to other antibiotics. It can be taken by mouth, as eye drops, as ear drops, or intravenously.
DNA topoisomerases are enzymes that catalyze changes in the topological state of DNA, interconverting relaxed and supercoiled forms, linked (catenated) and unlinked species, and knotted and unknotted DNA. Topological issues in DNA arise due to the intertwined nature of its double-helical structure, which, for example, can lead to overwinding of the DNA duplex during DNA replication and transcription. If left unchanged, this torsion would eventually stop the DNA or RNA polymerases involved in these processes from continuing along the DNA helix. A second topological challenge results from the linking or tangling of DNA during replication. Left unresolved, links between replicated DNA will impede cell division. The DNA topoisomerases prevent and correct these types of topological problems. They do this by binding to DNA and cutting the sugar-phosphate backbone of either one or both of the DNA strands. This transient break allows the DNA to be untangled or unwound, and, at the end of these processes, the DNA backbone is resealed. Since the overall chemical composition and connectivity of the DNA do not change, the DNA substrate and product are chemical isomers, differing only in their topology.
Levofloxacin, sold under the brand name Levaquin among others, is an antibiotic medication. It is used to treat a number of bacterial infections including acute bacterial sinusitis, pneumonia, H. pylori, urinary tract infections, Legionnaires' disease, chronic bacterial prostatitis, and some types of gastroenteritis. Along with other antibiotics it may be used to treat tuberculosis, meningitis, or pelvic inflammatory disease. Use is generally recommended only when other options are not available. It is available by mouth, intravenously, and in eye drop form.
The nucleoid is an irregularly shaped region within the prokaryotic cell that contains all or most of the genetic material. The chromosome of a typical prokaryote is circular, and its length is very large compared to the cell dimensions, so it needs to be compacted in order to fit. In contrast to the nucleus of a eukaryotic cell, it is not surrounded by a nuclear membrane. Instead, the nucleoid forms by condensation and functional arrangement with the help of chromosomal architectural proteins and RNA molecules as well as DNA supercoiling. The length of a genome widely varies and a cell may contain multiple copies of it.
DNA gyrase, or simply gyrase, is an enzyme within the class of topoisomerase and is a subclass of Type II topoisomerases that reduces topological strain in an ATP dependent manner while double-stranded DNA is being unwound by elongating RNA-polymerase or by helicase in front of the progressing replication fork. It is the only known enzyme to actively contribute negative supercoiling to DNA, while it also is capable of relaxing positive supercoils. It does so by looping the template to form a crossing, then cutting one of the double helices and passing the other through it before releasing the break, changing the linking number by two in each enzymatic step. This process occurs in bacteria, whose single circular DNA is cut by DNA gyrase and the two ends are then twisted around each other to form supercoils. Gyrase is also found in eukaryotic plastids: it has been found in the apicoplast of the malarial parasite Plasmodium falciparum and in chloroplasts of several plants. Bacterial DNA gyrase is the target of many antibiotics, including nalidixic acid, novobiocin, albicidin, and ciprofloxacin.
Nalidixic acid is the first of the synthetic quinolone antibiotics.
Topoisomerase IV is one of two Type II topoisomerases in bacteria, the other being DNA gyrase. Like gyrase, topoisomerase IV is able to pass one double-strand of DNA through another double-strand of DNA, thereby changing the linking number of DNA by two in each enzymatic step. Both share a hetero-4-mer structure formed by a symmetric homodimer of A/B heterodimers, usually named ParC and ParE.
Norfloxacin, sold under the brand name Noroxin among others, is an antibiotic that belongs to the class of fluoroquinolone antibiotics. It is used to treat urinary tract infections, gynecological infections, inflammation of the prostate gland, gonorrhea and bladder infection. Eye drops were approved for use in children older than one year of age.
Enoxacin is an oral broad-spectrum fluoroquinolone antibacterial agent used in the treatment of urinary tract infections and gonorrhea. Insomnia is a common adverse effect. It is no longer available in the United States.
Pefloxacin is a quinolone antibiotic used to treat bacterial infections. Pefloxacin has not been approved for use in the United States.
Cinoxacin is a quinolone antibiotic that has been discontinued in the U.K. as well the United States, both as a branded drug or a generic. The marketing authorization of cinoxacin has been suspended throughout the EU.
Topoisomerase inhibitors are chemical compounds that block the action of topoisomerases, which are broken into two broad subtypes: type I topoisomerases (TopI) and type II topoisomerases (TopII). Topoisomerase plays important roles in cellular reproduction and DNA organization, as they mediate the cleavage of single and double stranded DNA to relax supercoils, untangle catenanes, and condense chromosomes in eukaryotic cells. Topoisomerase inhibitors influence these essential cellular processes. Some topoisomerase inhibitors prevent topoisomerases from performing DNA strand breaks while others, deemed topoisomerase poisons, associate with topoisomerase-DNA complexes and prevent the re-ligation step of the topoisomerase mechanism. These topoisomerase-DNA-inhibitor complexes are cytotoxic agents, as the un-repaired single- and double stranded DNA breaks they cause can lead to apoptosis and cell death. Because of this ability to induce apoptosis, topoisomerase inhibitors have gained interest as therapeutics against infectious and cancerous cells.
In molecular biology Type I topoisomerases are enzymes that cut one of the two strands of double-stranded DNA, relax the strand, and reanneal the strand. They are further subdivided into two structurally and mechanistically distinct topoisomerases: type IA and type IB.
Type II topoisomerases are topoisomerases that cut both strands of the DNA helix simultaneously in order to manage DNA tangles and supercoils. They use the hydrolysis of ATP, unlike Type I topoisomerase. In this process, these enzymes change the linking number of circular DNA by ±2. Topoisomerases are ubiquitous enzymes, found in all living organisms.
Fleroxacin is a quinolone antibiotic. It is sold under the brand names Quinodis and Megalocin.
Flumequine is a synthetic fluoroquinolone antibiotic used to treat bacterial infections. It is a first-generation fluoroquinolone antibacterial that has been removed from clinical use and is no longer being marketed. The marketing authorization of flumequine has been suspended throughout the EU. It kills bacteria by interfering with the enzymes that cause DNA to unwind and duplicate. Flumequine was used in veterinarian medicine for the treatment of enteric infections, as well as to treat cattle, swine, chickens, and fish, but only in a limited number of countries. It was occasionally used in France to treat urinary tract infections under the trade name Apurone. However this was a limited indication because only minimal serum levels were achieved.
Difloxacin (INN), marketed under the trade name Dicural, is a second-generation, synthetic fluoroquinolone antibiotic used in veterinary medicine. It has broad-spectrum, concentration dependent, bactericidal activity; however, its efficacy is not as good as enrofloxacin or pradofloxacin.
Pradofloxacin, sold under the brand name Veraflox among others, is a third-generation enhanced spectrum veterinary antibiotic of the fluoroquinolone class. It was developed by Elanco Animal Health GmbH and received approval from the European Commission in April 2011, for prescription-only use in veterinary medicine for the treatment of bacterial infections in dogs and cats.
A circular chromosome is a chromosome in bacteria, archaea, mitochondria, and chloroplasts, in the form of a molecule of circular DNA, unlike the linear chromosome of most eukaryotes.
Quinolone antibiotics constitute a large group of broad-spectrum bacteriocidals that share a bicyclic core structure related to the substance 4-quinolone. They are used in human and veterinary medicine to treat bacterial infections, as well as in animal husbandry, specifically poultry production.
References
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- ↑ Zechiedrich, Elizabeth Lynn (1990). Catalytic mechanism of eukaryotic topoisomerase II (Thesis). OCLC 24362089.
- 1 2 3 4 "E. Lynn Zechiedrich, Ph.D."
- ↑ "Baylor researchers unravel mystery of DNA conformation". EurekAlert!. Retrieved November 19, 2021.
- ↑ "Research Casts New Light on 3D Structure of DNA | Sci-News.com". Breaking Science News | Sci-News.com. October 13, 2015. Retrieved November 19, 2021.
- ↑ Cepelewicz, Jordana (October 29, 2018). "Scientists Learn the Ropes on Tying Molecular Knots". Quanta Magazine. Retrieved November 19, 2021.
- 1 2 "Dynamic twists and loops can enable DNA to modulate its function". ScienceDaily. Retrieved November 19, 2021.
- ↑ "First videos to show the helix of 'dancing DNA' developed by scientists | News | The University of Sheffield". www.sheffield.ac.uk. February 16, 2021. Retrieved November 19, 2021.
- ↑ Leeds, University of (February 16, 2021). "Visualisation of 'dancing DNA'". www.leeds.ac.uk. Retrieved November 19, 2021.
- ↑ Saplakoglu, Yasemin (February 18, 2021). "Incredibly detailed video shows DNA twisting into weird shapes to squeeze into cells". livescience.com. Retrieved November 19, 2021.
- ↑ Hardee, Cinnamon L.; Arévalo-Soliz, Lirio Milenka; Hornstein, Benjamin D.; Zechiedrich, Lynn (February 10, 2017). "Advances in Non-Viral DNA Vectors for Gene Therapy". Genes. 8 (2): E65. doi: 10.3390/genes8020065 . ISSN 2073-4425. PMC 5333054 . PMID 28208635.
