N-terminal acetylation modulates peptide stability, fibrillogenesis and MMP-7 processing

Abstract

Short self-assembling peptides are versatile building blocks for enzyme-responsive nanostructured biomaterials. Here, we investigate how N -terminal acetylation affects the stability, fibrillogenesis, and protease-mediated fragment formation of two modular peptides, ug51 and ug52, composed of a fibrillogenic QAGIVV segment, an MMP-7-cleavable PLGL linker, and a C -terminal domain derived from motifs related to osteogenic growth peptides (OGPs). The stability of the peptides was assessed in water and cell culture medium, while secondary structure and nanoassembly were analyzed by circular dichroism, thioflavin T fluorescence, and transmission electron microscopy (TEM). Biological effects were evaluated in hFOB 1.19 osteoblasts. The non-acetylated peptide ug51 underwent spontaneous cleavage in the Val-Pro region, generating defined fragments, including PLGLYGFGG and, after prolonged incubation, the OGP-related LYGFGG sequence. In contrast, the N -terminally acetylated analog ug52 displayed markedly higher stability and formed ThT-positive, TEM-visible fibrillar assemblies. These assemblies remained susceptible to MMP-7-mediated processing, as shown by MALDI-TOF MS detection of the LYGFGG fragment after enzymatic incubation. Biological assays in hFOB 1.19 osteoblasts indicated overall cytocompatibility within the tested concentration range and peptide- and fragment-dependent effects on metabolic/proliferation-associated activity and migration-related responses. These findings suggest that N -terminal acetylation can shift the behavior of this modular peptide system from spontaneous degradation toward a more stable, fibril-forming, protease-processable state. Thus, this study provides proof-of-concept evidence that N -terminal acetylation can modulate the balance between peptide stability, supramolecular assembly, and enzymatic processability in a short modular peptide system. • N-terminal acetylation increases the apparent stability of the modular peptide ug52. • Non-acetylated ug51 undergoes spontaneous Val-Pro cleavage. • Acetylated ug52 forms ThT/TEM-positive fibrils that remain MMP-7-processable.