Elucidating the Inhibitory Potential of Designed Peptides Against Amyloid Fibrillation and Amyloid Associated Cytotoxicity

Abstract

Inhibition of fibrillation process and disaggregation of mature fibrils using small peptide are the promising remedial strategies to combat neurodegenerative diseases. However, designing peptide-based drugs to target β-sheet-rich amyloid has been a major challenge. The current work describes, for the first time, the amyloid inhibitory potential of the two short peptides (selected on the basis of predisposition of their amino acid residues toward β-sheet formation) using combination of biophysical, imaging methods, and docking approaches. Results showed that peptides employed different mechanisms to inhibit the amyloid fibrillation. Furthermore, they were also effective in blocking the amyloid fibrillation pathway. In contrary to the insulin fibrillar mesh, significantly less fibrillar species appeared in the presence of peptides, as confirmed by transmission electron microscopy. Circular dichroism analysis indicated that although peptides did not stabilize the native state of insulin, they inhibited amyloid aggregation by reducing the formation of β-sheet rich structures. Hemolytic assay revealed the non-hemolytic nature of the species formed when insulin was co-incubated with the peptides. Therefore, despite the inherent potential to form β-sheet structure, these peptides inhibited the amyloid formation and potentially can be used as therapeutics for the treatment of amyloid-related diseases.

Mobile obstacles accelerate and inhibit the bundle formation in two-patch colloidal particle

“…M particles surround B particles thereby completely exhausting their valencies. Siddiqi et al 56 studied the kinetics of formation of insulin fibres and observed that kinetic curve possesses a lag phase and after a certain time it increases in an exponential manner and a similar kinetic behavior is observed in this work, see Fig. 2a.…”

“…2a. In presence of peptide P4, the kinetics of formation of fibres is decreased by a factor of ∼ 5.6 56 . In our work in presence of C O = 0.5 fraction of M obstacles, < Z NPI > decreases by a factor of 5.36 at B att = 12 and t/t 0 = 1800.…”

Inhibitory effect of coumarin and its analogs on insulin fibrillation /cytotoxicity is depend on oligomerization states of the protein

“…In this study, our selected compounds had different effects on the brillation of insulin, both kinetically and morphologically. Also, not only does the secondary structure of brils play an important role in cytotoxicity (rely on the previous studies), [52][53][54] here, we found that overall organization, lateral connection and length of the brils are signicantly important in the effect of the aggregates on cell membrane disruption.…”

Stabilizing proteins to prevent conformational changes required for amyloid fibril formation

“…To generalize the aggregation‐inhibitory effect of IBFN, we also tested the anti‐amyloidogenic effect of this drug against human insulin fibrillation (Figure ). The ThT fluorescence intensity of insulin solution increased when protein was incubated at 65°C for 72 hours, suggesting the formation of amyloid‐like fibrils with the characteristic cross‐β structure . On the other hand, insulin samples co‐incubated with IBFN resulted in a pronounced decrease in the ThT fluorescence intensity, and this effect was concentration dependent.…”

“…The ThT fluorescence intensity of insulin solution increased when protein was incubated at 65°C for 72 hours, suggesting the formation of amyloid-like fibrils with the characteristic cross-β structure. 11,57 On the other hand, insulin samples coincubated with IBFN resulted in a pronounced decrease in the ThT fluorescence intensity, and this effect was concentration dependent. These observations suggested that IBFN is also able to block the insulin fibrillation.…”