Sodium fusidate prevents protein aggregation of silk fibroin and offers new perspectives for human lens material disaggregation

Effect of mono- and diketone group in curcumin analogues on amyloid fibrillation of hen egg white lysozyme

Curcumin has attracted more attention because of its inhibition efficacy on protein amyloid fibrillation. However, the inhibition mechanism was still ambiguous and the clinical application of curcumin was greatly limited because of its poor stability at physiological conditions for the presence of β-diketone moiety. In this paper, a new mono-ketone-containing curcumin analogue (MDHC) was designed and synthesized to realize the possible inhibition mechanism and unveil the important role of β-diketone moiety of curcumin in the inhibition process of amyloid fibrillation using hen egg white lysozyme (HEWL) as model protein. Although all experiment results (ThT, CR, ANS and TEM) showed that the inhibitory capacity of curcumin was better than MDHC, MDHC still could show obvious inhibition effect. Molecular docking showed that both curcumin and MDHC could bind with HEWL by hydrogen bond of phenloic hydroxyl and the binding energy of MDHC was higher than that of curcumin. All the findings inferred that β-diketone group was one of great important groups in the inhibition process of HEWL amyloid fibrillation, which provided more room to construct novel inhibition reagents.

Molecular docking of the pentapeptide derived from rice bran protein as anticancer agent inhibiting both receptor and non-receptor tyrosine kinases

The cationic pentapeptide Glu-Gln-Arg-Pro-Arg (EQRPR) belongs to the family of anti-cancer peptides with significant anti-cancer activity. However, the mechanism by which the peptide performs this activity is unknown. In this study, we explored the pharmaceutical profile of Glu-Gln-Arg-Pro-Arg pentapeptide and revealed its anticancer properties by in silico docking studies. Moreover, the effect of EQRPR behavior of the DPPC membrane was investigated by means of Langmuir monolayer technique and the results were discussed in terms of mutual interactions. To evaluate the binding mechanisms, the pentapeptide and its various D-amino acid substituted analogs were docked to both epidermal growth factor receptor (EGFR) tyrosine kinase and proto-oncogene tyrosine-protein kinase, Fyn. Simultaneous binding of the pentapeptides to both EGFR and Fyn proteins, which are receptor- and non-receptor-kinases, respectively, suggest that these peptides can be an effective agent for cancer treatment. Moreover, to show the potential of the investigated pentapeptides to overcome the generated mutation-related drug resistance to EGFR targeted therapies, molecular docking investigations of EQRPR and all its D-analogs were performed against the prospective targets: Wild type EGFR^WT and mutant EGFR^T790M. Erlotinib and TAK-285 were used as reference molecules. The strong interaction of the peptide with EGFR^WT (from -9.24 to -9.75 kcal/mol) and the secondary mutant EGFR^T790M (from -9.28 to -9.64 kcal/mol) observed in most cancer recurrence cases indicates its good potential to overcome drug resistance in cancer therapy. In addition, the pharmacological properties of the investigated pentapeptides were revealed by in silico ADME (Absorption, Distribution, Metabolism, Excretion) and toxicity analysis.Communicated by Ramaswamy H. Sarma.

Inhibitory effects of carbon quantum dots towards hen egg white lysozyme amyloidogenesis through formation of a stable protein complex

Proteins, under certain circumstances such as defective quality control mechanism, mutations and altered environmental conditions, undergo misfolding and assemble into highly ordered beta-sheet structured fibrillar aggregates called amyloid fibrils. Formation of amyloid is seen in most of the protein linked degenerative diseases like Alzheimer's disease, Parkinson's disease, Huntington's disease, Type II diabetes mellitus and many more. Amyloid fibril forms via intermediate state(s), and is known to follow a nucleated condensation polymerization mechanism. Though extensive research is being carried out towards finding a therapeutic solution to the amyloidosis, an effective treatment to these diseases still remains elusive and also the mechanism of amyloidogenesis largely remains unclear. In recent times, carbon quantum dots (CQDs) are gaining the attention of researchers due to their semi-conductive nature, excellent physio-chemical properties, high surface to volume ratio, optical properties and mainly bio-compatibility. In the current study, we have synthesized CQDs from commonly available kitchen spice mix and explored their role in amyloidogenesis using hen egg white lysozyme (HEWL) as a model protein. The results clearly demonstrate the amyloid inhibitory as well as disaggregation potential of CQD by forming a stable complex with HEWL and thereby increasing the energy barrier for the aggregation process.