77 by: Nathan Price
Student – Nathan Price
Name of Enzyme & E.C. number – Tryptophan Synthase; 2.1.20
Where is the enzyme found? Tryptophan Synthase is primarily found in bacteria, fungi, and plants. It is not found in animals or humans. Therefore, tryptophan is produced with the help of TrpS and must be obtained through dietary means because tryptophan is essential for protein synthesis.
What does the enzyme do? Tryptophan Synthase (TrpS) is a complex enzyme that catalyzes the final steps in producing the amino acid tryptophan (l-Trp). It has 2 active sites, connected by a tunnel, where reactions occur. The α-site breaks down a compound (IGP) to produce indole, which is transported to the β-active site through the tunnel. At the β-active site, indole reacts with another compound to form tryptophan, with the help of a cofactor called PLP. The two reactions are tightly coordinated through allosteric regulation (regulation where the regulatory activator or inhibitor molecule binds to an allosteric site separate from the active site), where changes in one active site influence the other, ensuring efficient tryptophan production without losing intermediates like indole.
Any other interesting facts or important information on your enzyme – The crucial feature of this enzyme is the “tunnel” that connects the two active sites. It helps enhance reaction efficiency and reduces loss or side reactions of intermediates. Substrate channeling from α-site to β-site occurs through a 25 Å tunnel.
References
Barends, T. R., Dunn, M. F., & Schlichting, I. (2008). Tryptophan synthase, an allosteric molecular factory. Current Opinion in Chemical Biology, 12(5), 593–600. https://doi.org/10.1016/j.cbpa.2008.07.011
Dierkers, A. T., Niks, D., Schlichting, I., & Dunn, M. F. (2009). Tryptophan synthase: Structure and function of the monovalent cation site. Biochemistry, 48(46), 10997–11010. https://doi.org/10.1021/bi9008374
Fatmi, M. Q., & Chang, C. A. (2010). The role of oligomerization and cooperative regulation in protein function: The case of tryptophan synthase. PLoS Computational Biology, 6(11). https://doi.org/10.1371/journal.pcbi.1000994
Information on EC 4.2.1.20 – tryptophan synthase. Information on EC 4.2.1.20 – tryptophan synthase – BRENDA Enzyme Database. (n.d.). https://www.brenda-enzymes.org/enzyme.php?ecno=4.2.1.20
Raboni, S., Bettati, S., & Mozzarelli, A. (2009). Tryptophan synthase: A mine for enzymologists. Cellular and Molecular Life Sciences, 66(14), 2391–2403. https://doi.org/10.1007/s00018-009-0028-0
