Investigating the inhibitory effect of azo-dyes on the activity of chorismate synthases from various organisms

In the 1950s, Bernhard Davis and David Sprinson discovered a biosynthetic route to the aromatic amino acids phenylalanine, tryptophan, and tyrosine. As this metabolic pathway is only present in prokaryotes, fungi, and plants, mammals need to get aromatic amino acids from their diet.
The inhibition of this pathway can eventually lead to cell death because each step of the shikimate pathway comprises an essential reaction in chorismate synthesis, which cannot be bypassed by any alternative enzyme. This knowledge makes the shikimate pathway a promising target for the development of antibacterial agents and herbicides.
From the seven enzymes of the pathway, chorismate synthase (CS) was chosen as a drug target because of its unique catalytic mechanism. Suitable CS inhibitors were selected using a combination of virtual screening and molecular dynamics performed by Seixas and co workers1,2.
Various methods were used to investigate the interaction of the enzymes and the obtained inhibitory compounds. Among other parameters, dissociation constants (1.1-4.4 µM) and IC50 values (10-16 µM) were determined by using a binding and inhibition assay, respectively. To get a better insight into the binding mode, crystallization of CS-inhibitor complexes is under progress.
Binding of the inhibitory compound to the enzymes could be confirmed, whereby the class of azo-dyes turned out to be a promising group of antifungal drugs. To improve the binding of the inhibitory compounds to CSs the active site will be investigated in more detail. Nevertheless, a crystal structure of an enzyme-inhibitor complex is required to design new compounds with improved binding affinity (nm-range).