Peptide binding studyzeta potential. Hf-BTB-NH2 solution (1 mg/ml) in diluted PBS (1.37 mmol wrt. NaCl) was incubated for 1 h with various concentrations of the three identified binding peptides. Zeta potentials were determined after 1 h of incubation to examine any change in this parameter for the various peptides. The equation for Kd is provided in section 4.1 of the Supporting Information.