Action of Papain on an IgG molecule produces?
**Core Concept**
The underlying principle being tested involves the enzymatic cleavage of immunoglobulins, specifically IgG, by the proteolytic enzyme **papain**. This process is significant in understanding the structure and function of antibodies. **Papain** cleaves IgG into distinct fragments.
**Why the Correct Answer is Right**
Papain acts on the IgG molecule by cleaving it into three fragments: two **Fab fragments** (fragment antigen-binding) and one **Fc fragment** (fragment crystallizable). The Fab fragments retain the ability to bind to antigens, while the Fc fragment interacts with cell surface receptors called Fc receptors and some proteins of the complement system.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not accurately describe the primary products of papain digestion of IgG.
**Option B:** Incorrect as it misrepresents the fragments produced.
**Option C:** Incorrect because, although it mentions fragments, it does not specify the correct ones produced by papain.
**Clinical Pearl / High-Yield Fact**
Remembering that **papain** digestion of IgG yields two **Fab** and one **Fc** fragment is crucial. This knowledge is vital for understanding antibody function and structure.
**Correct Answer:** D. Two Fab and one Fc fragment.