Sulfa Drugs

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  • Topic: Antibiotic, Sulfonamide, Bacteria
  • Pages : 2 (608 words )
  • Download(s) : 122
  • Published : April 28, 2013
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In the 1930’s, Richard Dogmagk experimented with a red dye called prontosil and found that it had strange healing effects, when he injected the dye into mice with severe streptococcus infections, they all survived. Dogmagk had discovered the one of the fist antibiotics, specifically the first Sulfa drug. When scientists isolated the active part of the prontosil molecule they discovered how it and all sulfa drugs work. Sulfa drugs contain a sulfur atom that has six total bonds (shared electrons) and six electrons of its own; this breaks the octet rule which states that atoms try to acquire eight electrons in their outer shell (not 12). Sulfur (and phosphorus) is element 16 on the periodic table; its elections are far enough to pond relatively freely with other atoms but close enough to be pulled by the nucleus strongly. This property allows it to share all its electrons stably. Sulfa drugs like sulfonamide, the active part of prontosil, disrupt the production of folic acid in bacteria. By mimicking the substrate of an enzyme, the enzyme is blocked and stops functioning (the substrate is what the enzyme converts or changes). Bacteria need to create folic acid in order to replicate their DNA and subsequently reproduce, once that is disrupted, the bacteria die off. Basically, sulfonamide is birth control for bacteria. Humans get folic acid from food, it is not produced in the cells and that is why sulfa drugs don’t affect human cells. From this discovery, selective toxicity emerged for drugs, meaning they affect only bacteria and not humans. Sulfa drugs, being antibiotics, allow bacteria develop resistance over time, meaning they stop to work after enough use. For this reason, sulfa drugs are typically used with another type of drug, trimethoprim. Together, these drugs block two enzymes and greatly reduce the probability of bacteria developing resistance to the drugs making them much more effective and useful.  

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