Catalytically active peptides affected by self-assembly and residues order

Amphiphilic peptides that induce catalysis are interesting alternatives to natural enzymes thanks to robustness of their synthesis and the ability to induce certain types of conformations by specific motifs of amino acid sequences. Various studies aimed at mimicking the activity of serine proteases by designed peptides. Here we demonstrate that the order by which the catalytic triad residues are positioned along amphiphilic beta-strands influences both assembly structures and catalytic activity. A set of three beta-sheet amphiphilic peptides, decorated with different orders of the catalytic triad amino acids, Glu, His and Ser along the strands were evaluated for their catalytic hydrolysis efficiency of p-nitrophenyl acetate (pNPA) substrate. Among the three peptides, Ac-CysPhe-Glu-Phe-Ser-Phe-His-Phe-Pro-NH2 (ESH) achieved the greatest catalytic efficiency with a value of 0.19 M-1 s(-1), at peptide concentration of 250 mu M. This study sheds light on an overlooked factor in designing catalytic amphiphilic assemblies whereby charged residues that make up the active sites, are in fact engaged in intermolecular stabilizing interactions that in turn may hamper their catalytic action.