Describe the digestive role of chymotrypsin. Which two other digestive enzymes of the same category are secreted by its source gland ?

Chymotrypsin is a digestive enzyme that plays a crucial role in the breakdown of proteins into smaller peptides during the process of digestion. It is produced and secreted by the pancreas as an inactive precursor called chymotrypsinogen. Chymotrypsinogen is activated into its active form, chymotrypsin, by the proteolytic enzyme trypsin, which is also secreted by the pancreas.

The digestive role of chymotrypsin involves the hydrolysis of peptide bonds within protein molecules, particularly those adjacent to aromatic amino acids such as tyrosine, phenylalanine, and tryptophan. Here's how chymotrypsin functions in the digestion of proteins:

1. Activation: Chymotrypsinogen is released from the pancreas into the duodenum along with other pancreatic enzymes in response to hormonal signals such as cholecystokinin (CCK). Once in the duodenum, chymotrypsinogen is activated into chymotrypsin by trypsin, which cleaves off a small peptide fragment from chymotrypsinogen, converting it into its active form.

2. Substrate Specificity: Chymotrypsin exhibits specificity for peptide bonds adjacent to aromatic amino acids in proteins. It cleaves these peptide bonds by hydrolyzing them, resulting in the formation of smaller peptide fragments.

3. Hydrolysis of Peptide Bonds: Chymotrypsin catalyzes the hydrolysis of peptide bonds within protein molecules, breaking them down into shorter peptides. This process involves the addition of a water molecule to the peptide bond, resulting in the separation of the amino acid residues on either side of the bond.

4. Formation of Peptide Fragments: As chymotrypsin cleaves peptide bonds, it generates a mixture of smaller peptide fragments with varying lengths. These peptide fragments are further broken down into individual amino acids by other digestive enzymes, such as carboxypeptidases and aminopeptidases, to facilitate their absorption by the intestinal epithelium.

In addition to chymotrypsin, the pancreas secretes two other digestive enzymes of the same category, known as serine proteases or serine endopeptidases. These enzymes are trypsin and elastase:

1. Trypsin: Like chymotrypsin, trypsin is produced as an inactive precursor called trypsinogen and is activated by enteropeptidase, an enzyme produced by the duodenal mucosa. Trypsin hydrolyzes peptide bonds adjacent to positively charged amino acids such as lysine and arginine.

2. Elastase: Elastase is another serine protease secreted by the pancreas. It is involved in the digestion of elastin, an insoluble protein found in connective tissues. Elastase cleaves peptide bonds adjacent to small amino acids such as glycine and alanine in elastin molecules.

Overall, chymotrypsin, along with trypsin and elastase, plays a critical role in the digestion of proteins by breaking them down into smaller peptides, which can then be further digested into individual amino acids for absorption in the small intestine.