University:
Liberty University
Course:
BIOM 500 | Introduction to Biomedical Sciences
Academic year:

2024
Views:

211

Pages:

6
Author:

Sheha A.

Digestion of Protein in Small Intestine Most protein digestion occurs in the small intestine, specifically the duodenum and jejunum, by proteolytic enzymes from pancreatic secretion. Pancreatic juice containing the endopeptidases like trypsin, chymotrypsin, and elastase and exopeptidases like carboxypeptidases. All these enzymes are secreted as zymogens which are converted to active 'zymases'. Enterokinase present on the intestinal microvillus membrane activates trypsinogen to trypsin. Trypsin then auto-catalyses its own activation and also catalyses the activation of chymotrypsinogen, proelastase, and procarboxypeptidases to chymotrypsin, elastase, and carboxypeptidases respectively. Activation of Pancreatic Proteolytic Enzymes Trypsinogen --> Enterokinase --> Trypsin Chymotrypsinogen --> Trypsin --> Chymotrypsin Proelastase --> Trypsin --> Elastase Procarboxypeptidase --> Trypsin --> Carboxypeptidase Enzymes Hydrolysis of bonds formed by carboxyl group of Pepsin Phe, Tyr, Trp, Met Trypsin Arg, Lys Chymotrypsin Phe, Tyr, Trp, Val, Leu (Aromatic and large neutral amino acid) Elastase Ala, Gly, Ser (Small amino acid residues) Carboxypeptidases It hydrolyzes carboxyl-terminal peptide bonds of polypeptides and oligopeptides produced by the action of endopeptidases. It hydrolyzes one amino acid at a time. Aminopeptidases It hydrolyzes one amino acid at a time by attacking the peptide bonds next to the amino terminal amino acids of polypeptides and oligopeptides. Intestinal juice also contains amino peptidases, dipeptidases and tripeptidases.