Enterokinase is an activator of:
**Core Concept**
Enterokinase is a serine protease enzyme produced in the duodenum that plays a crucial role in the activation of trypsinogen, a zymogen secreted by the pancreas. This enzyme is essential for initiating the digestive process in the small intestine.
**Why the Correct Answer is Right**
Enterokinase, also known as enteropeptidase, cleaves the activation peptide from trypsinogen, converting it into the active enzyme trypsin. This activation cascade is critical for the subsequent activation of other pancreatic enzymes, including chymotrypsin and carboxypeptidase. The enterokinase-trypsinogen interaction is a key event in the initiation of pancreatic enzyme activation.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because enterokinase is not involved in the activation of chymotrypsinogen; this process is mediated by trypsin.
**Option B:** Incorrect because enterokinase is not involved in the activation of prothrombin; this process is mediated by thrombin.
**Option C:** Incorrect because enterokinase is not involved in the activation of plasminogen; this process is mediated by urokinase.
**Clinical Pearl / High-Yield Fact**
Remember that enterokinase is a duodenal enzyme that activates trypsinogen, initiating the cascade of pancreatic enzyme activation. This process is essential for the digestion of proteins in the small intestine.
**Correct Answer:** D.