Heme oxygenase: Difference between revisions
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{{STRUCTURE_2dy5| PDB=2dy5 | SIZE=300| SCENE= |right| CAPTION=Rat heme oxygenase complex with imidazole derivative, Cl ion, [[2dy5]] }} | {{STRUCTURE_2dy5| PDB=2dy5 | SIZE=300| SCENE= |right| CAPTION=Rat heme oxygenase complex with imidazole derivative, Cl ion, [[2dy5]] }} | ||
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==='''Structure'''=== | ==='''Structure'''=== | ||
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HO is a 233 residue protein with a secondary structure consisting of <scene name='Sandbox_Reserved_308/7_helces/1'> seven α-helices </scene> which interacts with a <scene name='Sandbox_Reserved_308/Heme_group/1'> heme group </scene> <ref name="HO"/> at the optimum pH of 7.4; at 37 degrees C <ref name="PH">PMID:2158889</ref>. The heme is sandwiched between two helices termed the <scene name='Sandbox_Reserved_308/Prox_dis/1'> proximal and distal helices </scene> <ref name="HO3">PMID:18798608</ref>. The proximal helix provides the His 25 heme ligand along with the various contact residues (Ala 28 and Glu 29), but also Thr 21 which contacts the heme through a water molecule <ref name="HO"/>. On the distal side where the ligands binds (the catalytic site) there is a highly conserved sequence of Glycine residues (<scene name='Sandbox_Reserved_308/Test/4'>Gly 139, Gly 143-144</scene>) that provide a required flexibility for the reaction to occur <ref name="HO"/>. This results in the backbone atoms of Gly 139 and Gly 143 to directly contact the heme. Inhibition of HO is provided by compounds such as imidazole-dioxolane which disrupt this flexibility, thereby forcing the HO protein to become rigid, stopping its function <ref name="sc2">PMID:3290025</ref>. | HO is a 233 residue protein with a secondary structure consisting of <scene name='Sandbox_Reserved_308/7_helces/1'> seven α-helices </scene> which interacts with a <scene name='Sandbox_Reserved_308/Heme_group/1'> heme group </scene> <ref name="HO"/> at the optimum pH of 7.4; at 37 degrees C <ref name="PH">PMID:2158889</ref>. The heme is sandwiched between two helices termed the <scene name='Sandbox_Reserved_308/Prox_dis/1'> proximal and distal helices </scene> <ref name="HO3">PMID:18798608</ref>. The proximal helix provides the His 25 heme ligand along with the various contact residues (Ala 28 and Glu 29), but also Thr 21 which contacts the heme through a water molecule <ref name="HO"/>. On the distal side where the ligands binds (the catalytic site) there is a highly conserved sequence of Glycine residues (<scene name='Sandbox_Reserved_308/Test/4'>Gly 139, Gly 143-144</scene>) that provide a required flexibility for the reaction to occur <ref name="HO"/>. This results in the backbone atoms of Gly 139 and Gly 143 to directly contact the heme. Inhibition of HO is provided by compounds such as imidazole-dioxolane which disrupt this flexibility, thereby forcing the HO protein to become rigid, stopping its function <ref name="sc2">PMID:3290025</ref>. | ||