Papain acts an gamma globulin to form –
**Core Concept**
Papain is a proteolytic enzyme extracted from the papaya plant, used in various biochemical and immunological assays. It cleaves proteins at specific sites, often used to activate immunoglobulins (antibodies) for various applications.
**Why the Correct Answer is Right**
Papain acts as a gamma globulin activator by cleaving the S-S (disulfide) bonds in the Fc region of IgG antibodies, converting them into Fab and Fc fragments. This process is crucial for various immunological assays, such as ELISA (Enzyme-Linked Immunosorbent Assay). The activated IgG molecules can then bind to their respective antigens, making them useful for detecting specific antibodies in a sample.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because papain's action on immunoglobulins is specific to the Fc region, not the constant region.
**Option B:** Incorrect as papain is not known to activate IgM or IgA antibodies.
**Option C:** Incorrect because papain's action on immunoglobulins is not related to complement fixation.
**Clinical Pearl / High-Yield Fact**
Remember that papain activation of IgG antibodies is a critical step in various immunological assays, such as ELISA, which relies on the specific binding of antibodies to their respective antigens.
**Correct Answer:** C. Fc fragment.