Your book describes a treatment for -Thalassemia, a diseasewhere the body cannot make the form of hemoglobin. Transfusions arenecessary to provide the body with external sources ofï¢ï€hemoglobinbut that procedure causes a potentially fatal buildup of Fe in thebofy. To eliminate Fe2+, desferrioxamine B (DB) is given topatients. DB is a chelating agent for Fe2+ that has threehydroxamate groups which complex with the Fe or H. The hydroxamategroup in its uncomplexed basic form is
   O- O
   |   ||
R-N-C-R’
In this formula, R and R’ stand for other carbon-containingparts. When dB is administered to patients, it chelates with theFe2+ in three spots forming a Fe2+-DB complex with a formationconstant of 5 x 1030. The Fe2+-DB complex can then be excreted fromthe body.
a) Assume the body has a blood volume of 4.8 liters, theconcentration of Fe2+ in the blood is 3.6 x 10-5 M, and the bloodpH is 7.1. Assume that 200 mgm of DB is administered to a patient(DB has a molecular weight of 555) and the DB goes completely intothe patient’s blood system. Determine the concentration ofuncomplexed Fe that remains after the administration. The aciddissociation constants for DB are
K1 = 5 x 10-5
K2 = 6 x 10-6
K3 = 8 x 10-8
b) How many grams of Fe2+ will be removed from the patient’sbody if all the Fe2+ - D is excreted? (atomic weight of Fe =55)
c) If the number of grams determined in part b) are removed eachday, how many days will it take to remove the 4 grams of iron thattypically accumulate in a person’s body over 1 year?
