Citrate Synthase: Difference between revisions
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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/4'>active site</scene> of citrate synthase participate in acid-base catalysis: His 274, His 320, and Asp 375. First, <scene name='Daniel_Eddelman_Sandbox_2/Asp_375/1'>Asp 375</scene> (a base) removes a proton from the methyl group of acetyl-CoA to form its enol. <scene name='Daniel_Eddelman_Sandbox_2/His_274/1'>His 274</scene> stabilizes the acetyl-CoA enolate by forming a hydrogen bond with the enolate oxygen. The enolate then nucleophilically attacks oxaloacetate’s carbonyl carbon, and | <scene name='Daniel_Eddelman_Sandbox_2/Cts_active_site/4' target='0' >active site</scene> of citrate synthase participate in acid-base catalysis: His 274, His 320, and Asp 375. First, <scene name='Daniel_Eddelman_Sandbox_2/Asp_375/1'>Asp 375</scene> (a base) removes a proton from the methyl group of acetyl-CoA to form its enol. <scene name='Daniel_Eddelman_Sandbox_2/His_274/1'>His 274</scene> stabilizes the acetyl-CoA enolate by forming a hydrogen bond with the enolate oxygen. The enolate then nucleophilically attacks oxaloacetate’s carbonyl carbon, and | ||
<scene name='Daniel_Eddelman_Sandbox_2/His_320/1'>His 320</scene> 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/His_320/1'>His 320</scene> 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. | ||