Peptide samples (PFK and variants) were prepared as described above and diluted to a final concentration of 0.2 mM using Hepes buffer at a concentration of 50 mM, pH 7.4. A solution of Amytracker-680 fluorescent dye was prepared by diluting the dye by 50 folds in DIW. 45 μL of each peptide sample were placed in a 384-well black plate and supplemented with 5 μL of Amytracker-680 solution (total dilution of Amytracker-680 in the sample upon mixing, x500 times, 0.002 mg/mL). The samples within the plate were incubated for 10 more minutes before fluorescence measurements. The samples' fluorescence was measured using a Biotek Synergy H1 plate reader (Biotek, Winooski, VT, USA) using 550 nm excitation and 650 nm emission.