You are examining digestive enzymes and their processes of activation. You have isolated a mutant form of one particular enzyme and found that it remains inactive in a mixture of digestive juices. The wild-type enzyme is normally activated by hydrolysis on the C-terminal side of Arg and Lys residues and you determine that the mutant enzyme contains Ser residues at these critical positions. Which of the following digestive enzymes is most likely responsible for activation of the wildtype enzyme in your studies?
A) aminopeptidase
B) carboxypeptidase
C) chymotrypsin
D) enteropeptidase
E) lysozyme

Question

Quizplus · Accepted Answer

Enteropeptidase is responsible for activating trypsinogen to trypsin by cleaving at the C-terminal side of lysine residues, which aligns with the activation mechanism described for the wild-type enzyme.  Trypsin is a pancreatic digestive enzyme derived from proteolytic cleavage of the precursor protein trypsinogen. Enteropeptidase is produced by cells of the duodenum. It is secreted from intestinal glands called the crypts of Lieberkühn following the entry of ingested food passing from the stomach. Enteropeptidase converts trypsinogen into its active form trypsin. Trypsin cleaves its target substrates on the C-terminal side of Arg and Lys residues.

You Are Examining Digestive Enzymes and Their Processes of Activation