Final answer:
The antigen binding site of immunoglobulins is formed by the interaction between the variable regions of the light (VL) and heavy (VH) chains, making answer b. VH:VL the correct one.
Step-by-step explanation:
The antigen binding site of immunoglobulins corresponds to the interaction between the variable region of the heavy chain (VH) and the variable region of the light chain (VL). The correct answer to which of the following corresponds to the antigen binding site of immunoglobulins is b. VH:VL.
Immunoglobulins, or antibodies, are Y-shaped molecules consisting of light and heavy chains, each with variable (V) and constant (C) regions. The variable regions of these chains are responsible for the antigen specificity of the antibody, and when VH and VL come together, they form the specific site that can bind to epitopes on antigens.
The light chain is made up of a VL region from the N-terminal to amino acid 108 and a CL region from amino acids 109 to 214. The heavy chain contains a VH region from the N-terminal to amino acid 118 and a CH region from amino acid 119 to the C-terminal at amino acid 446. The VL and VH regions interact to form the antigen-binding site, which is essential for the immune response against pathogens.