Protein E Can Bind to Two Different Proteins, S and I.The

question 46

Multiple Choice

Protein E can bind to two different proteins, S and I.The binding reactions are described by the following equations and values:
E + S → ES K_eq for ES = 10
E + I → EI K_eq for EI = 2
Given the equilibrium constant values, which one of the following statements is TRUE?

• A)E binds I more tightly than S.
• B)When S is present in excess, no I molecules will bind to E.
• C)The binding energy of the ES interaction is greater than that of the EI interaction.
• D)Changing an amino acid on the binding surface of I from a basic amino acid to an acidic one will probably make the free energy of association with E more negative.

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Definitions:

Internal Iliac Vein

A major vein that drains blood from the pelvis and lower abdominal wall into the common iliac vein.

Common Iliac Vein

A large vein that forms from the union of the internal and external iliac veins and returns blood to the heart from the lower limbs.

External Iliac Vein

A large vein that carries deoxygenated blood from the lower limbs back to the heart.

Great Saphenous Vein

The longest vein in the body, running along the length of the lower limb, it transports blood from the foot back up to the deep femoral vein in the thigh.