Citrate Synthase: Difference between revisions

<scene name='Daniel_Eddelman_Sandbox_2/Cts_open_monomer/2'>homodimer</scene>  of a single amino acid chain <scene name='Daniel_Eddelman_Sandbox_2/Cts_open_monomer/1'>monomer</scene>. Each identical subunit consists of a large and a small domain, and is comprised almost entirely of α helices (making it an all α protein).  In its free enzyme state, citrate synthase exists in “open” form, with its two domains forming a cleft containing the substrate (oxaloacetate) binding site (PDB: [[1cts]]) <ref>PMID:7120407</ref>.  When oxaloacetate binds, the smaller domain undergoes an 18° rotation, sealing the oxaloacetate binding site and resulting in the <scene name='Daniel_Eddelman_Sandbox_2/Closed_homodimer/1'>closed conformation of the homodimer</scene> (PDB: [[2cts]])<ref>PMID:7308213</ref>.  The conformational change is best illustrated via <scene name='User:Wayne_Decatur/1cts_to_2cts_(citrate_synthase)_morph_methods/1ctsto2ctsmorph/5'>a morph between the "open" and "closed" states</scene>. The conformational change not only prevents solvent from reaching the bound substrate, but also generates the acetyl-CoA binding site.  This presence of “open” and “closed” forms results in citrate synthase having Ordered Sequential kinetic behavior <ref name="voet" />.