Engineering water-soluble stand-alone beta-sandwich mimetics is a current challenge
because of the difficulties associated with tailoring long-range interactions. In
this work, single cis-(1R,2S)-2-aminocyclohexanecarboxylic acid mutations were introduced
into the edge strands of the eight-stranded beta-sandwich mimetic structures from
the betabellin family. Temperature-dependent NMR and CD measurements, together with
thermodynamic analyses, demonstrated that the modified peripheral strands exhibited
an irregular and partially disordered structure but were able to exert sufficient
shielding on the hydrophobic core to retain the predominantly beta-sandwich structure.
Although the frustrated interactions decreased the free energy of unfolding, the temperature
of the maximum stabilities increased to or remained at physiologically relevant temperatures.
We found that the irregular peripheral strands were able to prevent edge-to-edge association
and fibril formation in the aggregation-prone model. These findings establish a beta-sandwich
stabilization and aggregation inhibition approach, which does not interfere with the
pillars of the peptide bond or change the net charge of the peptide.