Martini 3 was expected to display weaker peptide-peptide affinities, since one of its development goals was to mitigate the over-aggregation seen in Martini 2. However, to observe almost no dimeric contacts between peptides over an aggregate 80+ µs per system indicates that this type of short proteins now interacts too little. Even transient peptide contacts shunned most of the more hydrophobic correct dimer interface, to instead cluster around polar/charged residues (Figure ). This hints at a possible overly hydrophilic character of the peptides. One of Martini 3's development decisions possibly related to this was the choice to model all backbone beads with the same polar-ity type (P2), regardless of secondary structure. In Martini 2 the backbone bead types in helical or sheet secondary structures (particle types, N0 and Nda, respectively) were the least polar among backbone types, much less than the random coil one (P5), and reflected a lower availability of the carbonyl and amide in establishing further hydrogen bonding .