Would you expect mannose 6 phosphate to have a higher Ka bin

Would you expect mannose 6 phosphate to have a higher Ka (binding affinity) for the mannose 6 phosphate receptor at a pH 5 or pH6? Explain your answer when looking at just the pH numbers.

Solution

Ans. mannose-6-phosphate has a higher binding affinity (Ka) for mannose-6-ohosphate receptors (MPR) at pH 6.0.

MRP exhibit optimum binding to the ligands at pH range 6 to 7. Lowering pH below 6 or increasing it above 7 decrease the affinity of MPR (protein) for the ligand. Change in pH interferes with the relative charges on the amino acids residues. It further may adversely affect H-bonding, ionic interactions, and other non-covalent interactions among residues in 3D folded protein, resulting reversible or irreversible loss of function.