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Use of a small peptide fragment as an inhibitor of insulin fibrillation process: a study by high and low resolution spectroscopy.

Banerjee V, Kar RK, Datta A, Parthasarathi K, Chatterjee S, Das KP, Bhunia A - PLoS ONE (2013)

Bottom Line: In vitro hemolytic activity of the peptide showed insignificant cytotoxicity against HT1080 cells.The insulin aggregation is probed due to the inter play of two key residues, Phe(B24) and Tyr(B26) monitored from molecular dynamics simulations studies.Further new peptide based leads may be developed from this nine residue peptide.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Bose Institute, Kolkata, India.

ABSTRACT
A non-toxic, nine residue peptide, NIVNVSLVK is shown to interfere with insulin fibrillation by various biophysical methods. Insulin undergoes conformational changes under certain stress conditions leading to amyloid fibrils. Fibrillation of insulin poses a problem in its long-term storage, reducing its efficacy in treating type II diabetes. The dissociation of insulin oligomer to monomer is the key step for the onset of fibrillation. The time course of insulin fibrillation at 62°C using Thioflavin T fluorescence shows an increase in the lag time from 120 min without peptide to 236 min with peptide. Transmission electron micrographs show branched insulin fibrils in its absence and less inter-fibril association in its presence. Upon incubation at 62°C and pH 2.6, insulin lost some α-helical structure as seen by Fourier transformed infra-red spectroscopy (FT-IR), but if the peptide is added, secondary structure is almost fully maintained for 3 h, though lost partially at 4 h. FT-IR spectroscopy also shows that insulin forms the cross beta structure indicative of fibrils beyond 2 h, but in the presence of the peptide, α-helix retention is seen till 4 h. Both size exclusion chromatography and dynamic light scattering show that insulin primarily exists as trimer, whose conversion to a monomer is resisted by the peptide. Saturation transfer difference nuclear magnetic resonance confirms that the hydrophobic residues in the peptide are in close contact with an insulin hydrophobic groove. Molecular dynamics simulations in conjunction with principal component analyses reveal how the peptide interrupts insulin fibrillation. In vitro hemolytic activity of the peptide showed insignificant cytotoxicity against HT1080 cells. The insulin aggregation is probed due to the inter play of two key residues, Phe(B24) and Tyr(B26) monitored from molecular dynamics simulations studies. Further new peptide based leads may be developed from this nine residue peptide.

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Related in: MedlinePlus

Principal component analysis (PCA) considering the essential dynamics of prime three eigenvectors viz. PCA1, PCA2 and PCA3.
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pone-0072318-g010: Principal component analysis (PCA) considering the essential dynamics of prime three eigenvectors viz. PCA1, PCA2 and PCA3.

Mentions: PCA is one of the important tools to describe the stochastic movement of macromolecular system. All the conformations sampled for simulation, were analyzed in terms of linear relationships between atomic motions using the first three prime eigenvectors. The correlation scatter plots link the motions of ‘related’ fluctuations with those of ‘total’ fluctuations in the system, and are directly related to their biophysical properties. Figure 10 shows the projections of first three principal components. All scatter data-points were categorized by color codes to give an approximation of the path followed by insulin-NK9 complex in the simulation time course. The scatter point corresponding to 10–50 ns shows the time portion of simulation where the complex adopted many of the conformational changes for finding favorable interaction between chain B and NK9. Interestingly, the atomic fluctuations seem to have converged in the next phase of analysis (50–75 ns) and were almost conserved as for global minima in the phase 75–100 ns. PCA helps to concluding that the structural conformations as obtained beyond 75 ns is more close to stable conformation at low pH conditions.


Use of a small peptide fragment as an inhibitor of insulin fibrillation process: a study by high and low resolution spectroscopy.

Banerjee V, Kar RK, Datta A, Parthasarathi K, Chatterjee S, Das KP, Bhunia A - PLoS ONE (2013)

Principal component analysis (PCA) considering the essential dynamics of prime three eigenvectors viz. PCA1, PCA2 and PCA3.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3756998&req=5

pone-0072318-g010: Principal component analysis (PCA) considering the essential dynamics of prime three eigenvectors viz. PCA1, PCA2 and PCA3.
Mentions: PCA is one of the important tools to describe the stochastic movement of macromolecular system. All the conformations sampled for simulation, were analyzed in terms of linear relationships between atomic motions using the first three prime eigenvectors. The correlation scatter plots link the motions of ‘related’ fluctuations with those of ‘total’ fluctuations in the system, and are directly related to their biophysical properties. Figure 10 shows the projections of first three principal components. All scatter data-points were categorized by color codes to give an approximation of the path followed by insulin-NK9 complex in the simulation time course. The scatter point corresponding to 10–50 ns shows the time portion of simulation where the complex adopted many of the conformational changes for finding favorable interaction between chain B and NK9. Interestingly, the atomic fluctuations seem to have converged in the next phase of analysis (50–75 ns) and were almost conserved as for global minima in the phase 75–100 ns. PCA helps to concluding that the structural conformations as obtained beyond 75 ns is more close to stable conformation at low pH conditions.

Bottom Line: In vitro hemolytic activity of the peptide showed insignificant cytotoxicity against HT1080 cells.The insulin aggregation is probed due to the inter play of two key residues, Phe(B24) and Tyr(B26) monitored from molecular dynamics simulations studies.Further new peptide based leads may be developed from this nine residue peptide.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Bose Institute, Kolkata, India.

ABSTRACT
A non-toxic, nine residue peptide, NIVNVSLVK is shown to interfere with insulin fibrillation by various biophysical methods. Insulin undergoes conformational changes under certain stress conditions leading to amyloid fibrils. Fibrillation of insulin poses a problem in its long-term storage, reducing its efficacy in treating type II diabetes. The dissociation of insulin oligomer to monomer is the key step for the onset of fibrillation. The time course of insulin fibrillation at 62°C using Thioflavin T fluorescence shows an increase in the lag time from 120 min without peptide to 236 min with peptide. Transmission electron micrographs show branched insulin fibrils in its absence and less inter-fibril association in its presence. Upon incubation at 62°C and pH 2.6, insulin lost some α-helical structure as seen by Fourier transformed infra-red spectroscopy (FT-IR), but if the peptide is added, secondary structure is almost fully maintained for 3 h, though lost partially at 4 h. FT-IR spectroscopy also shows that insulin forms the cross beta structure indicative of fibrils beyond 2 h, but in the presence of the peptide, α-helix retention is seen till 4 h. Both size exclusion chromatography and dynamic light scattering show that insulin primarily exists as trimer, whose conversion to a monomer is resisted by the peptide. Saturation transfer difference nuclear magnetic resonance confirms that the hydrophobic residues in the peptide are in close contact with an insulin hydrophobic groove. Molecular dynamics simulations in conjunction with principal component analyses reveal how the peptide interrupts insulin fibrillation. In vitro hemolytic activity of the peptide showed insignificant cytotoxicity against HT1080 cells. The insulin aggregation is probed due to the inter play of two key residues, Phe(B24) and Tyr(B26) monitored from molecular dynamics simulations studies. Further new peptide based leads may be developed from this nine residue peptide.

Show MeSH
Related in: MedlinePlus