For an equimolar mixture of CC-Di_E1 and MCL-1, the fitting of the sedimentation data indicated the 2:2 complex to be the only state present. Upon increasing the peptide concentration, the sedimentation peak broadened and shifted to a smaller sedimentation coefficient, consistent with the presence of smaller oligomers, however the fitted molecular weight was larger than a 2:1 CC-Di_E1:MCL-1 stoichiometry, indicating the 2:2 complex remained. This is consistent with the positive co-operative formation of a ternary complex, as indicated by the CD and Native NS data. For CC-Tri_E1, a small shift in the peak compared to MCL-1 was observed with the fitted molecular weight indicating peptide binding. Upon increasing peptide concentration, the peak broadened potentially indicating multiple states. For CC-Tet_E1, a peak with fitted mass in between 4:1 CC-Tet-E1:MCL-1 and 2:2 CC-Tet-E1:MCL-1 was observed. In addition, for the equimolar mixture of CC-Tet_E1 and MCL-1, a small peak corresponding to the weight of MCL-1 was observed, alongside an even smaller peak for a higher weight. At increased peptide ratios, a peak corresponding to a small weight appeared, likely unbound CC-Tet_E1 tetramer. Overall, native MS data, AUC and SEC data are broadly consistent across the coiled-coil series. Data for the homodimers show they can co-operatively recruit and bind two copies of MCL-1. AF2 modelling suggests this is possible and this is compatible with our interpretation of the unfolding experiments (Tm(dimer/MCL-1) > Tm(monomer/MCL1). For trimeric and teterameric coiled coils the data are more ambiguous. AF2 modelling suggests that binding of multiple copies of MCL-1 to trimer and tetramer is sterically constrained. Higher-order protein-peptide oligomers were not abundant in native MS, AUC or SEC experiments. Moreover, the inhibitory potencies for both are lower than monomeric controls whilst unfolding of complexes is comparable (Tm(oligomer/MCL-1) ~ Tm(monomer/MCL-1). This is consistent with a more complex equilibria where larger oligomers are able to recruit fewer copies of MCL-1, and so to maximize interactions, peptide/MCL-1 binding competes with coiled-coil oligomerization.