GLP – 1 is broken down by
**Core Concept**
GLP-1 (Glucagon-Like Peptide-1) is a naturally occurring incretin hormone involved in glucose metabolism. It is secreted by the intestinal L cells in response to nutrient intake and enhances insulin secretion, suppresses glucagon release, and delays gastric emptying.
**Why the Correct Answer is Right**
GLP-1 is primarily broken down by dipeptidyl peptidase-4 (DPP-4), also known as CD26. DPP-4 is a metalloprotease enzyme that cleaves the N-terminal dipeptide from GLP-1, thereby inactivating its biological activity. This breakdown occurs in the bloodstream, and the half-life of GLP-1 is significantly reduced due to this enzymatic activity.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not mentioned in the context of GLP-1 breakdown.
* **Option B:** While other enzymes may be involved in protein degradation, DPP-4 is the primary enzyme responsible for GLP-1 breakdown.
* **Option C:** This option is not a known enzyme involved in GLP-1 breakdown.
**Clinical Pearl / High-Yield Fact**
DPP-4 inhibitors are a class of oral antidiabetic drugs that work by blocking the action of DPP-4, thereby increasing the levels of active GLP-1 and enhancing glucose-dependent insulin secretion.
**Correct Answer: C. Dipeptidyl peptidase-4 (DPP-4)**