Sandbox Reserved 789
From Proteopedia
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<scene name='56/563201/Water_interactions/1'>Water molecules</scene> are represented by the blue spheres, are present on the surface of the enzyme. | <scene name='56/563201/Water_interactions/1'>Water molecules</scene> are represented by the blue spheres, are present on the surface of the enzyme. | ||
| - | Citrate synthase has two ligands that bind to it: oxaloacetate and coenzyme A. The <scene name='56/563201/Ligand_interactions/2'>oxaloacetate ligand</scene>is represented in purple, in ball and stick and the rest of the protein is in ribbon. The citrate synthase homodimer exists in two forms. In its free enzyme state it exists in its <scene name='56/563201/Homodimer/3'>open</scene> conformation, where the binding site for oxaloacetate is exposed. When oxaloacetate binds, the alpha helices that stick slightly outward fold slightly inward, sealing off the oxaloacetate binding site. This results in a dramatic conformational change; now the enzyme is in its <scene name='56/563201/Homodimer_closed/2'>closed</scene> conformation. The conformational change exposes the acetyl-CoA binding site. | + | Citrate synthase has two ligands that bind to it: oxaloacetate and coenzyme A. The <scene name='56/563201/Ligand_interactions/2'>oxaloacetate ligand</scene>is represented in purple, in ball and stick and the rest of the protein is in ribbon. The citrate synthase homodimer exists in two forms. In its free enzyme state it exists in its <scene name='56/563201/Homodimer/3'>open</scene> conformation, where the binding site for oxaloacetate is exposed. When oxaloacetate binds, the alpha helices that stick slightly outward fold slightly inward, sealing off the oxaloacetate binding site. This results in a dramatic conformational change; now the enzyme is in its <scene name='56/563201/Homodimer_closed/2'>closed</scene> conformation. The conformational change exposes the acetyl-CoA binding site. The <scene name='56/563201/Catalytic_residues/1'>catalytic residues</scene>, where the ligand binds to the protein, are shown in black. The catalytic residues are Asp375, His274, His320, Ser244. |
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Revision as of 03:39, 17 October 2013
| This Sandbox is Reserved from Oct 10, 2013, through May 20, 2014 for use in the course "CHEM 410 Biochemistry 1 and 2" taught by Hanna Tims at the Messiah College. This reservation includes Sandbox Reserved 780 through Sandbox Reserved 807. |
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Citrate synthase exists in nearly all cells, and is responsible for catalyzing the first reaction in the citric acid cycle: the condensation of acetyl-CoA and oxaloacetate to form citrate. Citrate synthase consists of 437 amino acids, which are organized in to two identical subunits. Citrate synthase is considered a of a single amino acid chain monomer, this makes up its tertiary structure. Each subunit consists of 20 alpha-helices. Alpha-helices make up the majority of the enzymes , with few beta sheets. The a- helices are represented in purple, while the B- sheets are in blue.
The in the backbone are depicted in yellow. Hydrogen bonding is what holds the molecule together, most notably the secondary structure. Based on the hydrogen bonding in the beta sheets, it is evident, by the straight hydrogen bonds, that they are anti-parallel to each other.
Here the , depicted in gray, are for the most part, in the interior of the enzyme, while the , depicted in purple, are on the outer surface of the enzyme. Based on this depiction, it is evident that there more hydrophobic residues than hydrophilic residues. Furthermore,there is an abundance of hydrophobic residues exposed to the surface on the side of the enzyme where the binding site is located. This due to the fact that citrate synthase forms a homodimer. The area where hydrophobic residues are on the surface is at the subunit-subunit interface. Thus, this is the hydrophobic core or the dimer.
are represented by the blue spheres, are present on the surface of the enzyme.
Citrate synthase has two ligands that bind to it: oxaloacetate and coenzyme A. The is represented in purple, in ball and stick and the rest of the protein is in ribbon. The citrate synthase homodimer exists in two forms. In its free enzyme state it exists in its conformation, where the binding site for oxaloacetate is exposed. When oxaloacetate binds, the alpha helices that stick slightly outward fold slightly inward, sealing off the oxaloacetate binding site. This results in a dramatic conformational change; now the enzyme is in its conformation. The conformational change exposes the acetyl-CoA binding site. The , where the ligand binds to the protein, are shown in black. The catalytic residues are Asp375, His274, His320, Ser244.
