Sandbox Reserved 1605: Difference between revisions
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=== Hemes === | === Hemes === | ||
Three <scene name='83/832931/Heme/6'>hemes</scene> are present in the CydA subunit. These three hemes form a triangle to maximize subunit stability<ref name="Safarian">PMID:31604309</ref><ref name="Theßeling">PMID:31723136</ref><ref name="Rajendran">PMID:27126043</ref>, which is an evolutionary conserved feature across bd oxidases<ref name="Safarian">PMID:31604309</ref>. Heme b<sub>558</sub> acts as the primary electron acceptor by catalyzing the oxidation of quinol<ref name="Theßeling">PMID:31723136</ref>. Conserved <scene name='83/832931/Met393/1'>His186 and Met393</scene> help to stabilize heme b558<ref name="Theßeling">PMID:31723136</ref>. Heme b<sub>558</sub> transfers the electrons to heme b595, which transfers them to the active site heme d<ref name= "Safarian">PMID:31604309</ref>. A conserved <scene name='83/832931/Trp441/5'>Trp441</scene> assists heme b<sub>595</sub> in transferring electrons to heme d<ref name="Rajendran">PMID:27126043</ref>. A conserved <scene name='83/832931/Hemeb595/2'>Glu445</scene> is essential for charge stabilization of heme b<sub>595</sub><ref name="Theßeling">PMID:31723136</ref>, while <scene name='83/832931/Hemeh19/2'>His19</scene> stabilizes heme d<ref name="Rajendran">PMID:27126043</ref>. As heme d collects the electrons from heme b<sub>595</sub>, <scene name='83/832931/Heme_d/2'>Glu99</scene> in the o-channel facilities the binding of oxygen to heme d, and <scene name='83/832931/Heme_d/2'>Ser109, Glu107, and Ser140</scene> in the h-channel facilitate proton transfer to heme d<ref name="Safarian">PMID:31604309</ref>. | Three <scene name='83/832931/Heme/6'>hemes</scene> are present in the CydA subunit. These three hemes form a triangle to maximize subunit stability<ref name="Safarian">PMID:31604309</ref><ref name="Theßeling">PMID:31723136</ref><ref name="Rajendran">PMID:27126043</ref>, which is an evolutionary conserved feature across bd oxidases<ref name="Safarian">PMID:31604309</ref>. Heme b<sub>558</sub> acts as the primary electron acceptor by catalyzing the oxidation of quinol<ref name="Theßeling">PMID:31723136</ref>. Conserved <scene name='83/832931/Met393/1'>His186 and Met393</scene> help to stabilize heme b558<ref name="Theßeling">PMID:31723136</ref>. Heme b<sub>558</sub> transfers the electrons to heme b595, which transfers them to the active site heme d<ref name= "Safarian">PMID:31604309</ref>. A conserved <scene name='83/832931/Trp441/5'>Trp441</scene> assists heme b<sub>595</sub> in transferring electrons to heme d<ref name="Rajendran">PMID:27126043</ref>. A conserved <scene name='83/832931/Hemeb595/2'>Glu445</scene> is essential for charge stabilization of heme b<sub>595</sub><ref name="Theßeling">PMID:31723136</ref>, while <scene name='83/832931/Hemeh19/2'>His19</scene> stabilizes heme d<ref name="Rajendran">PMID:27126043</ref>. As heme d collects the electrons from heme b<sub>595</sub>, <scene name='83/832931/Heme_d/2'>Glu99</scene> in the o-channel facilities the binding of oxygen to heme d, and <scene name='83/832931/Heme_d/2'>Ser109, Glu107, and Ser140</scene> in the h-channel facilitate proton transfer to heme d<ref name="Safarian">PMID:31604309</ref>. | ||
Similar to the hemes, the <scene name='83/832931/Uq8/3'>ubiquinone-8</scene> (UQ-8) molecule found in CydB mimics the triangular formation to stabilize the subunit<ref name= "Safarian">PMID:31604309</ref>. | Similar to the three hemes, the <scene name='83/832931/Uq8/3'>ubiquinone-8</scene> (UQ-8) molecule found in CydB mimics the triangular formation to stabilize the subunit<ref name="Safarian">PMID:31604309</ref>. | ||
===Mechanism=== | ===Mechanism=== | ||
Quinol is used as the initial electron donor (Fig. 4) and heme b<sub>558</sub> is the initial electron acceptor. Heme b<sub>558</sub> will pass the electrons to heme b<sub>595</sub>, which passes the electrons to heme d. Concurrently, the h-channel will collect hydrogen atoms and o-channel will collect oxygen atoms that will flow to heme d (Fig. 3). With electrons, oxygen, and protons available, heme d can successfully reduce dioxygen to water. | Quinol is used as the initial electron donor (Fig. 4) and heme b<sub>558</sub> is the initial electron acceptor. Heme b<sub>558</sub> will pass the electrons to heme b<sub>595</sub>, which passes the electrons to heme d. Concurrently, the h-channel will collect hydrogen atoms and o-channel will collect oxygen atoms that will flow to heme d (Fig. 3). With electrons, oxygen, and protons available, heme d can successfully reduce dioxygen to water. | ||