53 by: Samuel Kjeldsen-Trotter

Student – Samuel Kjeldsen-Trotter

Name of Enzyme & E.C. Number: Pepsin A (Pepsin) with E.C. Number 3.4.23.1

Where is pepsin A found? Pepsin A is found in the gastric juice of the stomach in vertebrates (BRENDA, 2023).

What does the enzyme do? Pepsin A is the stomach’s major gastric proteolytic endopeptidase, which functions in the internal cleavage of peptide bonds (Barrett et al., 2013, pp. li, 27–32). Pepsin “preferentially hydrolyzes peptide linkages where one of the amino acids is aromatic” (DrugBank Online, n.d.). It plays an important role in the breakdown of proteins into smaller peptides and AAs in the stomach.

Interesting Facts or Important Information – Chief cells in the stomach release pepsinogen, an inactive precursor to pepsin. Pepsinogen contains a 44 amino acid propeptide (tail) which is removed upon entering the stomach’s acidic environment, activating it into pepsin (Barrett et al., 2013, p. 30). Pepsin has a hydrophobic pocket stabilizing the aromatic AA it preferentially binds next to (Elsässer & Goettig, 2021). To clear up any confusion, my randomly assigned enzyme was pepsin, but because there are different types, I chose “pepsin A”, which is commonly referred to as pepsin.

References
Barrett, A. J., Rawlings, N. D., & Woessner, F. (2012). Handbook of Proteolytic Enzymes (3rd ed., Vol. 1, pp. li, 27–32). Academic Press.

BRENDA. (2023). Information on EC 3.4.23.1 – pepsin A. BRENDA. https://www.brenda-enzymes.org/enzyme.php?ecno=3.4.23.1

DrugBank Online. (n.d.). Pepsin. DrugBank. Retrieved September 28, 2024, from https://go.drugbank.com/drugs/DB13198

Elsässer, B., & Goettig, P. (2021). Mechanisms of Proteolytic Enzymes and Their Inhibition in QM/MM Studies. International Journal of Molecular Sciences, 22(6). https://doi.org/10.3390/ijms22063232