Question 8 (1 point) Which of these statements about ligand binding to proteins is false? Binding is reversible Ligand binds to a region on the protein surface that is structurally complementary A $$K_d$$ of $$10^{-6}$$ M reflects weaker binding than a $$K_d$$ of $$10^{-4}$$ M The $$K_d$$ is the free ligand concentrations at which the ligand binding sites are 50% saturated A $$K_d$$ of 10 nM reflects tighter binding than a $$K_d$$ of 10 µM
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The question asks to identify the false statement about ligand binding to proteins. This requires knowledge of fundamental concepts in biochemistry and molecular biology related to protein-ligand interactions and the dissociation constant ($$K_d$$). Show more…
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11. Which one of the following statements about protein-ligand binding is correct? A) The Ka (association constant) is equal to the concentration of ligand when all of the binding sites are occupied. B) The Ka is equal to the concentration of ligand when 50% of the binding sites are occupied. C) The larger the Ka, the weaker the binding affinity. D) The larger the Ka, the smaller the Kd (dissociation constant). E) The Kd is a concentration of ligand when θ < 0.5.
Sri K.
Indicate whether each of the following statements about the heme-binding site in myoglobin is true or false. If you think a statement is false, explain why: (a) The proximal histidine covalently binds iron. (b) The distal histidine covalently binds oxygen. (c) The distal histidine binds iron. (d) Free heme binds CO with the Fe, C, and O atoms in a linear array. (e) The iron in heme binds the oxygen atom of CO. Protein A has a binding site for ligand X with a Kd of 10^-6. Protein B has a binding site for ligand X with a Kd of 10^-9 M. Which protein has a higher affinity for ligand X? Explain your reasoning. Convert Kd to Ka for both proteins.
2 a.) A protein has binding affinity for its ligand (a peptide) of Ka = 2 x105 M -1 at pH 5.0 and 25oC. At what concentration of the ligand is one third of the protein bound? b.) What fraction of the protein is bound at ligand concentration of 1.0 μM ? c.) At what ligand concentration will be 60% of the protein bound? d.) When the pH was raised to 6.5, the Kd increased to 20 μM. Is the binding tighter or weaker at this pH compared to pH5.0? Explain why. e.) What functional group (amino acid) is most likely responsible for this change in the binding affinity with pH?
Supreeta N.
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