What is the functional role of the "distal histidine"? It binds tightly to the heme iron to stabilize the complex between iron and oxygen. It stabilizes the complex between Fe2+ and dioxygen. It donates a hydrogen bond to the bound oxygen molecule to stabilize the complex between iron and oxygen. It stabilizes the oxygen complex and catalyzes the oxidation of iron to the ferric state. It improves access of carbon monoxide to the heme and inhibits oxidation of iron to the ferric state.
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Step 1: The distal histidine residue in hemoglobin is involved in hydrogen bonding with the molecular oxygen (O2) when it is bound to the iron atom in the porphyrin ring. Show moreā¦
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The role of the proximal histidine in hemoglobin is to: Select one: a. oxidize Fe(II) b. assist in oxygen uptake c. reduce Fe(III) d. assist in oxygen release In Crystal Field theory, the uniform crystal field: Select one: a. unifies the orbitals into one set b. stabilizes the orbitals c. destabilizes the orbitals d. splits the orbitals into two sets
Sri K.
When oxygen binds to a subunit of hemoglobin, the T conformation of hemoglobin shifts to the R state. The distal histidine (His-64) moves away from the O2, decreasing the affinity for iron. The distal histidine (His-64) is bound to water. The R conformation of hemoglobin shifts to the T state. The proximal histidine (His-93) is bound to oxygen.
Adi S.
The binding of oxygen by hemoglobin (Hb), giving oxyhemoglobin (HbO,), is partially regulated by the concentration of $\mathrm{H}_{3} \mathrm{O}^{+}$ and dissolved $\mathrm{CO}_{2}$ in the blood. Although the equilibrium is complicated, it can be summarized as $\mathrm{HbO}_{2}(a q)+\mathrm{H}_{3} \mathrm{O}^{+}(a q)+\mathrm{CO}_{2}(g) \rightleftharpoons \mathrm{CO}_{2}-\mathrm{Hb}-\mathrm{H}^{+}+\mathrm{O}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l)$ (a) Write the equilibrium constant expression for this reaction. (b) Explain why the production of lactic acid and $\mathrm{CO}_{2}$ in a muscle during exertion stimulates release of $\mathrm{O}_{2}$ from the oxyhemoglobin in the blood passing through the muscle.
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