Based on the location of this residue and the differences between Lys and Asp, suggest a rationale for the observed reduction in O2-binding affinity. The charge on the side chain can form salt bridges with the other side chains in the BPG- binding pocket and stabilize the state.
In essence, the side chain is mimicking the charge on BPG.

a. negative
b. (-) charged
c. R
d. T
e. Positive
f. (+)charged
g. Lys
h. Asp