Hemoglobin (Hb) protein transport `O_2` in blood and each Hb can bind `4O_2`, molecules. In discussing protein oxygen binding capacity, biochemists use a measure called the `P^50` value, defined as the partial pressure of oxygen at which 50% of hemoglobin is saturated. Fetal hemoglobin has a `P^50` value of 20 torr and adult has `P^50` value of 40 torr. For the following equilibrium:
`4O_(2)(g) + Hb (aq) to [Hb(O_(2))_(4)(aq)]`
What is the value of `K_("fetal")// K_("adult")` ?
[Where K represents equilibrium constant.]

Answer

A

Explanation

`K_("fetal") = ([Hb)(O_(2))_(4)]/([Hb].P_(O_(2))^(4)) = ([Hb(O_(2))_(4)])/([Hb] xx ("20 torr"^(4))`
`K_("adult") = ([Hb (O_(2))_(4)])/([Hb] xx ("40 torr")^(4))`
`therefore K_("fetal")/K_("adult") = (40/20)^(4) = 16`