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-	In the first step of the reaction, Histidine-156 abstracts a proton from the 3-hydroxyl of chloramphenicol, promoting a nucleophilic attack from the deprotonated oxygen onto the thioester bond of the acetyl-CoA. The 3-acetylchloramphenicol intermediate then rearranges, non-enzymatically, to a 1-acetylchloramphenicol intermediate. CAT III then causes another acetylation of the now regenerated 3-hydroxyl and 1,3-diacetylchloramphenicol is produced.	+	In the first step of the reaction, Histidine-156 abstracts a proton from the 3-hydroxyl of chloramphenicol, promoting a nucleophilic attack from the deprotonated oxygen onto 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 CAT III catalyzed nucleophilic attack to another acetyl-CoA and a 1,3-diacetylchloramphenicol product is formed.

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Revision as of 04:26, 21 March 2010

Anthony Daniele

Chloramphenicol Acetyltransferase Type III

Chloramphenicol acetyltransferase type III (CAT III) is an enzyme which catalyzes the transfer of acetyl from acetyl-CoA to hydroxyl groups of chloramphenicol. CAT III is a trimeric protein

Introduction

Reaction of CAT III

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In the first step of the reaction, Histidine-156 abstracts a proton from the 3-hydroxyl of chloramphenicol, promoting a nucleophilic attack from the deprotonated oxygen onto 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 CAT III catalyzed nucleophilic attack to another acetyl-CoA and a 1,3-diacetylchloramphenicol product is formed.

Please do NOT make changes to this Sandbox until after April 23, 2010. Sandboxes 151-200 are reserved until then for use by the Chemistry 307 class at UNBC taught by Prof. Andrea Gorrell.