Question

A biochemist working with Hb purified from blood performs a series of in vitro experiments. She is able to further purify Hb which results in two separate and distinct samples: Stripped Hb and Blood Hb. Blood Hb has a sigmoidal theta plot with a normal p50 value of ~40 mm Hg. Stipped Hb appears hyperbolic with a p50 value of ~2 mm Hg. Interestingly, when she adds very high concentrations of NaCl to the Blood Hb oxygen binding reactions, the result is a decrease in p50 for Blood Hb to ~2 mm Hb. Which of the following experimental factors are most likely responsible for the observed results?

A) The NaCl is likely preventing the Blood Hb from undergoing a T to R transition and therefore the result is a decrease in p50
B) The NaCl is probably disrupting the quaternary and tertiary structure of Blood Hb resulting in the decrease in p50 and leading to a hyperbolic theta plot
C) At high concentrations in solution, the Na+ ions are likely binding to Bohr positions resulting in the decrease in Blood Hb p50
D) At high concentrations in solution, the Na+ ions are likely forming ionic interactions with the proximal and distal histidine residues thus decreaseing the p50 value
E) At high concentrations in solution, the Cl- ions are probably out competing 2,3 BPG for the binding site in the central cavity of Blood Hb resulting in a decrease in p50

Answer 1

Option E

Step-by-step explanation:

At high concentrations in solution, the Cl- ions are probably out competing 2,3 BPG for the binding site in the central cavity of Blood Hb resulting in a decrease in p50