Sandbox 156: Difference between revisions
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Both reactions take place in the active site of CAT III, where acetyl-CoA is tunneled through from the opposing side of the trimer<ref name="Leslie">PMID: 3288984</ref>. | Both reactions take place in the active site of CAT III, where acetyl-CoA is tunneled through from the opposing side of the trimer<ref name="Leslie">PMID: 3288984</ref>. | ||
[[Image:Presentation3.jpg|frame| | [[Image:Presentation3.jpg|frame|500x450 px|center|Reaction mechanism of CAT III]] | ||
In the first step of the reaction, Histidine-195 abstracts a proton from the 3-hydroxyl of chloramphenicol, promoting a [http://en.wikipedia.org/wiki/Nucleophilic_attack nucleophilic attack] from the [http://en.wikipedia.org/wiki/Oxyanion oxyanion] to the thioester bond of the acetyl-CoA. The intermediate produced, 3-acetylchloramphenicol, then rearranges non-enzymatically to 1-acetylchloramphenicol. Regeneration of the 3-hydroxyl allows another round of CAT III catalyzed nucleophilic attack and a 1,3-diacetylchloramphenicol product is formed<ref name="Murray"/>. | In the first step of the reaction, Histidine-195 abstracts a proton from the 3-hydroxyl of chloramphenicol, promoting a [http://en.wikipedia.org/wiki/Nucleophilic_attack nucleophilic attack] from the [http://en.wikipedia.org/wiki/Oxyanion oxyanion] to the thioester bond of the acetyl-CoA. The intermediate produced, 3-acetylchloramphenicol, then rearranges non-enzymatically to 1-acetylchloramphenicol. Regeneration of the 3-hydroxyl allows another round of CAT III catalyzed nucleophilic attack and a 1,3-diacetylchloramphenicol product is formed<ref name="Murray"/>. | ||
