C. Citrate synthase enzyme activity measurements performed in vitro. V. cholerae GltA and F383A GltA proteins were purified using a 6xHis tag in E. coli. Both the proteins were treated without the synthesized VcdP or VcdP* peptide, or with increasing concentrations of the two peptides (1x, 2x, 5x, 10x, 15x or 20x with respect to the protein monomer). The citrate synthase activity per milligram of protein as a result of its interaction with the peptide was determined from the initial velocities. 