Final answer:
Proteolytic enzymes enhance antigen properties for many molecules but do not enhance the antigen-binding properties of the Fc fragment of an immunoglobulin. Hence, the answer to the question is D. S.
Step-by-step explanation:
The question is addressing the interaction of antigens with proteolytic enzymes. Proteolytic enzymes enhance the immunogenic properties of some antigens, but not all. In the case of the IgG molecule, treatment with the enzyme papain does not enhance the antigen-binding of the Fc (fragment crystallizable) portion, it only separates the molecule into Fab and Fc fragments.
Therefore, the correct answer to the question 'All of the following antigens are interacted (enhanced) by proteolytic enzymes except: A. Fya B. C C. M D. S' is D. S, presuming 'S' refers to the Fc fragment of an immunoglobulin, which does not bind to the antigen and thus would not have its antigen-binding properties enhanced by proteolytic digestion.