Protein-protein interactions (PPIs) drive and regulate many biological functions. Understanding the molecular mechanism by which protein-protein interactions occur is central to understanding function.(4) Such mechanistic understanding can support development of: tools that can modulate PPIs to act as probes of healthy and disease states of biological processes, and drug discovery efforts. Many PPIs employ short peptides for recognition ; aside from serving as templates for designing PPI inhibitors , a feature of short recognition peptides is that they are often intrinsically disordered and undergo disorder-order transitions, e.g., to form α-helices or β-strands on PPI formation. The association binding kinetics of coupled folding and binding are influenced by the larger hydrodynamic radius, flexibility and folding propensity of IDPs in comparison to folded proteins, alongside the abundance of exposed charged residues which are often associated with encounter complex formation. IDPs in their apo form can also populate a bound-folded state to support a conformational selection binding mechanism. Whilst IDPs that populate a helical bound conformation can be easily evidenced by NMR chemical shifts, β-strand conformations are more challenging to characterise; a propensity to form extended structures is normally captured by NMR, but the extended ensemble typically contains numerous conformations, only some of which are binding-competent. The synthetic accessibility of peptides makes them ideal tools to study biomolecular mechanisms; modifications that alter the conformational landscape of a disordered peptide can be used to bias the energy landscape to probe binding mechanisms in a systematic way. N-methylation of backbone amides has been shown to improve the affinity, interaction specificity, solubility, membrane permeability, and proteolytic stability of peptides. However, these studies have generally focused on cyclic peptides. There are far fewer reports on N-methylation of linear peptides, and even fewer for peptides solely composed of L-amino acids.(25-27)(28) N-methylation can restrict the conformations accessible to a peptide, as it disfavours backbone conformations in the bottom-left quadrant of the Ramachandran plot, which includes the α-helical region, ϕ ≈ -60° and ψ ≈ -50°. However, it also allows access to alternative conformations by lowering the difference in stability between cis/trans amide rotamers. Nonetheless, the precise manner in which N-methylation can be used to alter the backbone conformational preferences of linear peptides, in particular understanding what determines the extent to which N-methylation favours more-extended structures, is less explored. N-methylation also changes the hydrogen-bonding capabilities of peptides. In turn, this could alter the ability of a peptide to bind to protein targets, but it can also improve the physical properties of peptides; for instance, reducing propensities to self-assemble into amyloid-like structures, and susceptibilities to certain proteases. Thus, in this work, we sought to explore the extent to which backbone N-methylation might serve as a tool to inform on and modulate IDP binding mechanism; using the interaction between small ubiquitin-like modifiers (SUMO) and SUMO-interacting motifs (SIMs) as a model to explore the effects of N-methylating a SIM peptide, we show that whilst backbone modification of some sites abrogates binding, at others it increases the peptide-protein association rate (kon) resulting in increased binding affinity. For the latter, this behaviour can be rationalized as follows: N-methylation restricts the accessible peptide conformations, in effect predisposing them for target recognition. This is achieved by raising the energy of the unbound state, and decreasing the activation energy (entropy) required for binding. Such an approach may therefore represent an effective method by which to enhance protein binding affinity of disordered regions, and design peptidomimetic inhibitors of β-strand-mediated PPIs.