Language：English   Publishing type：Research paper (scientific journal)  

A simple NMR method to analyze the data obtained by NMR titration experiment of amyloid formation inhibitors against uniformly 15N-labeled amyloid-β 1-42 peptide (Aβ(1-42)) was described. By using solution nuclear magnetic resonance (NMR) measurement, the simplest method for monitoring the effects of Aβ fibrilization inhibitors is the NMR chemical shift perturbation (CSP) experiment using 15N-labeled Aβ(1-42). However, the flexible and dynamic nature of Aβ(1-42) monomer may hamper the interpretation of CSP data. Here we introduced principal component analysis (PCA) for visualizing and analyzing NMR data of Aβ(1-42) in the presence of amyloid inhibitors including high concentration osmolytes. We measured 1H-15N 2D spectra of Aβ(1-42) at various temperatures as well as of Aβ(1-42) with several inhibitors, and subjected all the data to PCA (PCA-HSQC). The PCA diagram succeeded in differentiating the various amyloid inhibitors, including epigallocatechin gallate (EGCg), rosmarinic acid (RA) and curcumin (CUR) from high concentration osmolytes. We hypothesized that the CSPs reflected the conformational equilibrium of intrinsically disordered Aβ(1-42) induced by weak inhibitor binding rather than the specific molecular interactions.

DOI： 10.1016/j.abb.2020.108446

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Language：English   Publishing type：Research paper (scientific journal)  

The molecular shield effect was studied for intrinsically disordered proteins (IDPs) that do not adopt compact and stable protein folds. IDPs are found among many stress-responsive gene products and cryoprotective- and drought-protective proteins. We recently reported that some fragments of human genome-derived IDPs are cryoprotective for cellular enzymes, despite a lack of relevant amino acid sequence motifs. This sequence-independent IDP function may reflect their molecular shield effect. This study examined the inhibitory activity of IDPs against fibril formation in an amyloid beta peptide (Aβ(1-42)) model system. Four of five human genome-derived IDPs (size range 20 to 44 amino acids) showed concentration-dependent inhibition of amyloid formation (IC50 range between 60 and 130 μM against 20 μM Aβ(1-42)). The IC50 value was two orders of magnitude lower than that of polyethylene-glycol and dextran, used as neutral hydrophilic polymer controls. Nuclear magnetic resonance with 15 N-labeled Aβ(1-42) revealed no relevant molecular interactions between Aβ(1-42) and IDPs. The inhibitory activities were abolished by adding external amyloid-formation seeds. Therefore, IDPs seemed to act only at the amyloid nucleation phase but not at the elongation phase. These results suggest that IDPs (0.1 mM or less) have a molecular shield effect that prevents aggregation of susceptible molecules.

DOI： 10.1038/s41598-020-69129-1

PubMed

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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