Sandbox Reserved 1716: Difference between revisions
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The cap domain of Vitamin K Epoxide Reductase plays an intricate role in its function. When Vitamin K Epoxide (or a similar substrate) binds in the hydrophobic pocket of VKOR, the cap domain undergoes a conformational change that will allow for specific cysteine residues to be able to open the epoxide ring and to recreate Vitamin K Quinone. The catalytic cycle begins in an open fully oxidized conformation. <scene name='90/904321/Openvkor/3'>Open Oxidized Conformation</scene> This conformation has slightly different parts. These include the Anchor (green), the cap region (blue), 3-4 Loop (pink), and luminal helix (yellow). When Vitamin K Epoxide binds, the entire cap domain undergoes a slight conformation change, but the luminal helix has a larger change. The luminal helix (yellow) bends forward where specific cysteines on this region are in proximity to other important cysteines. The luminal helix is then referred to as the beta hairpin (purple). <scene name='90/904321/Vkoclosed/3'>Partially Oxidized Closed Conformation</scene> | The cap domain of Vitamin K Epoxide Reductase plays an intricate role in its function. When Vitamin K Epoxide (or a similar substrate) binds in the hydrophobic pocket of VKOR, the cap domain undergoes a conformational change that will allow for specific cysteine residues to be able to open the epoxide ring and to recreate Vitamin K Quinone. The catalytic cycle begins in an open fully oxidized conformation. <scene name='90/904321/Openvkor/3'>Open Oxidized Conformation</scene> This conformation has slightly different parts. These include the Anchor (green), the cap region (blue), 3-4 Loop (pink), and luminal helix (yellow). When Vitamin K Epoxide binds, the entire cap domain undergoes a slight conformation change, but the luminal helix has a larger change. The luminal helix (yellow) bends forward where specific cysteines on this region are in proximity to other important cysteines. The luminal helix is then referred to as the beta hairpin (purple). <scene name='90/904321/Vkoclosed/3'>Partially Oxidized Closed Conformation</scene> | ||
=Catalytic Cysteines= | |||
A set of four | A set of four catalytic are required for Vitamin K Epoxide reduction and are consistently conserved in all VKOR homologs. In the human homolog (HsVKOR) these cysteines are Cys43, Cys51, Cys132, and Cys 135. <scene name='90/904321/Cysteines/6'>Significant Cysteines</scene> In the Pufferfish homolog (TrVKORL) these cysteines, due to Cryo-EM differences,are Cys52, Cys55, Cys141, and Cys144. These cysteines donate their electrons to the epoxide ring on Vitamin K Epoxide which reforms Vitamin K Quinone. In the closed active conformation, that is induced when Vitamin K binds in the hydrophobic pocket. (NEED TO FINISH) | ||
