The approach has been inverted to exploit cysteines present within a peptide ligand to create "covalent-molecular glues"; fragment-peptide hybrids linked via a disulfide. Similarly, imine based tethering has subsequently been described whereby aldehydes react with surface exposed lysine residues on the surface of 14-3-3 to stabilize its interaction with peptides. A further complementary approach, whereby a scaffold compatible with dynamic combinatorial exchange by virtue of a central acylhydrazone bond, was used as a template to identify small-molecule 14-3-3ζ/synaptopodin stabilizers. We recently used ligand-directed fragment ligation as a tool to identify peptide-fragment hybrids that inhibit a β-strand mediated PPI. Reliant, on hydrazone exchange this approach is advantageous in that it unites the synthesis and assay steps within a single step and rapidly explores SAR using commercially available aldehyde fragments. Inspired also by the work of Ohkanda on the use of oxime ligation for in situ assembly of a bivalent diterpenepeptide conjugate as an intracellular 14-3-3ζ inhibitor, in this work we used our recently reported data on the hDMX/14-3-3 interaction 27 as a model to further elaborate acylhydrazone-based ligand-directed fragment ligation to identify PPI inhibitory peptidefragment hybrids which upon separation into the components can yield fragments as candidate PPI stabilizers (Fig. ). In contrast to the earlier work on covalent protein- and peptide-based molecular glues, this approach allowed us to reveal that non-covalent fragments which stabilize PPIs can be identified using site-directed ligation methods. Furthermore, the two methods are complementary in terms of the conditions under which the bonds are stable and under which exchange occurs. Finally, the asymmetry of the hydrazone linkage when compared to the disulfide, may be advantageous in terms of yielding only unsymmetrical peptide fragment hybrids. Reversible acylhydrazone reactions are used to generate peptide fragment hybrids using a template protein (here: 14-3-3η); inhibitors are then separated into peptide and fragment components for evaluation as stabilizers; (b) A cluster of small organic probes (orange spheres) were modelled at the interface between hDMX361-374 pSer367 (cyan sticks) and 14-3-3σ-ΔC dimer (green) using FTMap (c) peptide sequences used.