Under appropriate conditions, hemoglobin dissociates into its four subunits. The isolated alpha subunit binds oxygen, but the O2 saturation curve is hyperbolic rather than sigmoid. In addition the binding of oxygen to the isolated subunit is not affected by the presence of CO2. Explain why in 2-3 sentences. (why sigmoid ,why not affected by CO2 )
The sigmoid-shaped binding curve of hemoglobin in its native form is due to cooperative binding, meaning that binding of one oxygen molecule facilitates the binding of subsequent molecules. This cooperative binding is lost when hemoglobin dissociates into its individual subunits, resulting in a hyperbolic curve. The binding of oxygen to the isolated alpha subunit is not affected by CO2 because CO2 primarily binds to the beta subunits of hemoglobin, causing a conformational change that promotes oxygen unloading.
