Citrate Synthase: Difference between revisions

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Daniel Eddelman, David Canner, Wayne Decatur, Michal Harel, Eric Martz, Alexander Berchansky, Angel Herraez, Joel L. Sussman

Revision as of 07:00, 28 February 2010 view source Daniel Eddelman (talk \| contribs) 58 edits →‎The Structure and Mechanism of Citrate Synthase ← Older edit		Revision as of 07:05, 28 February 2010 view source Daniel Eddelman (talk \| contribs) 58 edits →‎The Structure and Mechanism of Citrate Synthase Newer edit →
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	'''Mechanism:''' The reaction mechanism for citrate synthase was proposed by James Remington. In this mechanism, three ionizable side chains in the		'''Mechanism:''' The reaction mechanism for citrate synthase was proposed by James Remington. In this mechanism, three ionizable side chains in the
	<scene name='Daniel_Eddelman_Sandbox_2/Cts_active_site/1'>active site</scene> of citrate synthase participate in acid-base catalysis: His 274, His 320, and Asp 375. First, Asp 375 (a base) removes a proton from the methyl group of acetyl-CoA to form its enol. His 274 stabilizes the acetyl-CoA enolate by forming a hydrogen bond with the enolate oxygen. The enolate then nucleophilically attacks oxaloacetate’s carbonyl carbon, and His 320 donates a proton to oxaloacetate’s carbonyl group in a concerted step, forming citryl-CoA (which remains bound to the enzyme). Finally, citryl-CoA is hydrolyzed to citrate and CoA.		<scene name='Daniel_Eddelman_Sandbox_2/Cts_active_site/2'>active site</scene> of citrate synthase participate in acid-base catalysis: His 274, His 320, and Asp 375. First, Asp 375 (a base) removes a proton from the methyl group of acetyl-CoA to form its enol. His 274 stabilizes the acetyl-CoA enolate by forming a hydrogen bond with the enolate oxygen. The enolate then nucleophilically attacks oxaloacetate’s carbonyl carbon, and His 320 donates a proton to oxaloacetate’s carbonyl group in a concerted step, forming citryl-CoA (which remains bound to the enzyme). Finally, citryl-CoA is hydrolyzed to citrate and CoA.