Question

List three proteases and their sub-strates

Short answer

Trypsin (lysine or arginine), Pepsin (aromatic amino acids), Chymotrypsin (aromatic amino acids).

Step-by-step solution

Understand the Exercise

The task is to list three different proteases along with the specific substrates they act on.

Identify Proteases

Three well-known proteases include Trypsin, Pepsin, and Chymotrypsin.

Determine Substrates for Each Protease

1. Trypsin: This enzyme cleaves peptide bonds at the carboxyl side of the amino acids lysine or arginine.2. Pepsin: This enzyme breaks down proteins into smaller peptides; it prefers cleavage at the amino side of aromatic amino acids like phenylalanine, tryptophan, and tyrosine.3. Chymotrypsin: This enzyme preferentially cleaves at the carboxyl side of aromatic amino acids, particularly phenylalanine, tryptophan, and tyrosine.

Summarize

The three proteases identified are Trypsin (substrate: lysine or arginine residues), Pepsin (substrate: aromatic amino acids), and Chymotrypsin (substrate: aromatic amino acids).

Key concepts

Trypsin

Trypsin is a protease that plays a crucial role in digestion. It is produced in the pancreas as an inactive precursor called trypsinogen. When trypsinogen reaches the small intestine, it is activated into trypsin.
Trypsin works by breaking down proteins into smaller peptides. Specifically, it cleaves peptide bonds at the carboxyl side of the amino acids lysine and arginine. This is important because proteins need to be broken down into smaller pieces for the body to absorb them effectively.
Without trypsin, the body would struggle to digest and utilize proteins from food, leading to nutritional deficiencies.
To summarize:

• Trypsin is produced in the pancreas.
• It activates from trypsinogen in the small intestine.
• Cleaves at lysine and arginine.
• Essential for protein digestion.

Pepsin

Pepsin is another critical protease in the digestive system. Unlike trypsin, pepsin is active in the stomach. It is produced as an inactive enzyme called pepsinogen. The acidic environment of the stomach (pH 1.5 to 3.5) activates pepsinogen into pepsin.
Pepsin works by breaking down proteins into smaller peptides. It prefers cleavage at the amino side of aromatic amino acids such as phenylalanine, tryptophan, and tyrosine. This specificity helps in targeting and digesting a wide variety of dietary proteins.
Without pepsin, the initial stages of protein digestion in the stomach would be inefficient.
Key points:

• Pepsin is active in the acidic environment of the stomach.
• Activated from pepsinogen in low pH.
• Cleaves at aromatic amino acids.
• Essential for the first phase of protein digestion.

Chymotrypsin

Chymotrypsin is another protease involved in protein digestion. Like trypsin, it is produced in the pancreas as an inactive precursor called chymotrypsinogen. Chymotrypsinogen is activated into chymotrypsin in the small intestine.
Chymotrypsin specifically cleaves peptide bonds at the carboxyl side of aromatic amino acids, such as phenylalanine, tryptophan, and tyrosine. This enzyme works in concert with other proteases to break down dietary proteins into absorbable peptides and amino acids.
The action of chymotrypsin is critical for degrading proteins that are complex and difficult to digest.
In summary:

• Chymotrypsin is produced by the pancreas.
• Activated from chymotrypsinogen in the small intestine.
• Targets aromatic amino acids for cleavage.
• Works with other proteases for efficient protein digestion.