MINT MINT, Dpt of Biology, University of Rome Tor Vergata MINT http://mint.bio.uniroma2.it/mint url>http://mint.bio.uniroma2.it/mint/ https://mint.bio.uniroma2.it MINT-[0-9]+ https://mint.bio.uniroma2.it/index.php/results-interactions/?id=${ac} The Molecular INTeraction database (MINT) is a relational database designed to store interactions between biological molecules. http://mint.bio.uniroma2.it A hIAPP-derived all-d-amino-acid inhibits hIAPP fibrillation efficiently at membrane surface by targeting α-helical oligomeric intermediates. A hIAPP-derived all-d-amino-acid inhibits hIAPP fibrillation efficiently at membrane surface by targeting α-helical oligomeric intermediates. FEBS Lett. (0014-5793) 2014 imex curation Wang L., Lei L., Li Y., Wang L., Li F. feili@jlu.edu.cn 10-Mar-2014: Contacted by IntAct-Help. Only protein-protein interactions in vitro In vitro dls dynamic light scattering dls predetermined predetermined participant predetermined feili@jlu.edu.cn Accepted 2014-FEB-06 by LUANA 2014 imex curation A hIAPP-derived all-d-amino-acid inhibits hIAPP fibrillation efficiently at membrane surface by targeting α-helical oligomeric intermediates. A hIAPP-derived all-d-amino-acid inhibits hIAPP fibrillation efficiently at membrane surface by targeting α-helical oligomeric intermediates. FEBS Lett. (0014-5793) 2014 imex curation Wang L., Lei L., Li Y., Wang L., Li F. feili@jlu.edu.cn 10-Mar-2014: Contacted by IntAct-Help. Only protein-protein interactions in vitro In vitro fluorescence fluorescence technology fluorescence predetermined predetermined participant predetermined feili@jlu.edu.cn Accepted 2014-FEB-06 by LUANA 2014 imex curation A hIAPP-derived all-d-amino-acid inhibits hIAPP fibrillation efficiently at membrane surface by targeting α-helical oligomeric intermediates. A hIAPP-derived all-d-amino-acid inhibits hIAPP fibrillation efficiently at membrane surface by targeting α-helical oligomeric intermediates. FEBS Lett. (0014-5793) 2014 imex curation Wang L., Lei L., Li Y., Wang L., Li F. feili@jlu.edu.cn 10-Mar-2014: Contacted by IntAct-Help. Only protein-protein interactions in vitro In vitro tem transmission electron microscopy tem predetermined predetermined participant predetermined feili@jlu.edu.cn Accepted 2014-FEB-06 by LUANA 2014 imex curation A hIAPP-derived all-d-amino-acid inhibits hIAPP fibrillation efficiently at membrane surface by targeting α-helical oligomeric intermediates. A hIAPP-derived all-d-amino-acid inhibits hIAPP fibrillation efficiently at membrane surface by targeting α-helical oligomeric intermediates. FEBS Lett. (0014-5793) 2014 imex curation Wang L., Lei L., Li Y., Wang L., Li F. feili@jlu.edu.cn 10-Mar-2014: Contacted by IntAct-Help. Only protein-protein interactions in vitro In vitro atomic force microsc atomic force microscopy AFM AFM atomic force microsc predetermined predetermined participant predetermined feili@jlu.edu.cn Accepted 2014-FEB-06 by LUANA 2014 imex curation iapp_human Islet amyloid polypeptide IAPP Amylin Diabetes-associated peptide Insulinoma amyloid peptide protein protein human Homo sapiens Human MGILKLQVFLIVLSVALNHLKATPIESHQVEKRKCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTYGKRNAVEVLKREPLNYLPL DIP protein P10997 original sequence version: 138 not sure about the protein origin DIP protein P10997 original sequence version: 92 DIP protein P10997 original sequence version: 88 mint AA8B1F7FD9FCB4BD iapp-iapp-1 2 hIAPP 5 predetermined predetermined participant predetermined predetermined predetermined participant predetermined unspecified role unspecified role neutral component neutral component purified purified hIAPP 5 predetermined predetermined participant predetermined predetermined predetermined participant predetermined unspecified role unspecified role neutral component neutral component purified purified direct interaction direct interaction f1a f3a Firstly, we examined the inhibitory effect of the all-D-amino-acid inhibitor on the assembly of hIAPP in bulk solution. Similarly to the results of previous studies [30], an aggregation process from unstructured monomers to β-sheeted fibrils was observed for hIAPP alone in bulk solution, as indicated by the time-dependence of Thioflavin-T (ThT) fluorescence, transmission electron microscopy (TEM) image and circular dichroism (CD) spectra (Figure 1A-C). The addition of equimolar peptide inhibitor in bulk solution of hIAPP resulted in a complete suppression of ThT fluorescence intensity (Figure 1A) and disappearance of fibrils in TEM image where only small pieces with length around 200-300 nm were left (Figure 1D). We next examined the inhibitory effect of the all-D-amino-acid inhibitor under phospholipid membrane condition. Before addition of the inhibitor, the ThT fluorescence intensity of hIAPP in lipid vesicle solution displayed a rapid increase after ca. 5 min delay (Figure 3A), which is much less than that of hIAPP in bulk solution (corresponding time needed in bulk solution was ca. 2 h). The decrease in the lag time was attributed to the accelerating role of lipid membrane for fibril formation of the amyloid peptide which has been well established [41]. iapp-iapp-2 3 hIAPP 5 predetermined predetermined participant predetermined predetermined predetermined participant predetermined unspecified role unspecified role neutral component neutral component purified purified hIAPP 5 predetermined predetermined participant predetermined predetermined predetermined participant predetermined unspecified role unspecified role neutral component neutral component purified purified direct interaction direct interaction f1b f1d Firstly, we examined the inhibitory effect of the all-D-amino-acid inhibitor on the assembly of hIAPP in bulk solution. Similarly to the results of previous studies [30], an aggregation process from unstructured monomers to β-sheeted fibrils was observed for hIAPP alone in bulk solution, as indicated by the time-dependence of Thioflavin-T (ThT) fluorescence, transmission electron microscopy (TEM) image and circular dichroism (CD) spectra (Figure 1A-C). The addition of equimolar peptide inhibitor in bulk solution of hIAPP resulted in a complete suppression of ThT fluorescence intensity (Figure 1A) and disappearance of fibrils in TEM image where only small pieces with length around 200-300 nm were left (Figure 1D). iapp-iapp-3 1 hIAPP 5 predetermined predetermined participant predetermined predetermined predetermined participant predetermined unspecified role unspecified role neutral component neutral component purified purified hIAPP 5 predetermined predetermined participant predetermined predetermined predetermined participant predetermined unspecified role unspecified role neutral component neutral component purified purified direct interaction direct interaction f2 In order to confirm the difference in the dimensions of the aggregate species of hIAPP in bulk solution with and without inhibitor, we measured the size population in the process of hIAPP aggregation by the dynamic light scattering (DLS) experiments in both cases (Figure 2). In the absence of inhibitor, the growth of hIAPP particles from hydrodynamic diameter (d) of several nanometers (monomers) to several micrometers via intermediates with d smaller than 400 nm was clearly observed, along with the broadening of size distribution. In comparison with the case of hIAPP alone in bulk solution, the growth of the peptide in the presence of equimolar inhibitor stopped at ~2 h with a narrower population of d around 200-350 nm. iapp-iapp-4 4 hIAPP 5 predetermined predetermined participant predetermined predetermined predetermined participant predetermined unspecified role unspecified role neutral component neutral component purified purified hIAPP 5 predetermined predetermined participant predetermined predetermined predetermined participant predetermined unspecified role unspecified role neutral component neutral component purified purified direct interaction direct interaction f3b f3c f3d As show in Figure 3B-D, whereas abundant fibrils were formed at lipid membrane in the absence of the inhibitor, the amyloid fibrils were remarkably decreased when hIAPP was incubated with equimolar inhibitor. The fibrillation was even completely inhibited and a large amount of oligomers were present when threefold inhibitor was added. It was noted that very thin and elongated fibers are clearly present in AFM image at a molar ratio of hIAPP:inhibitor = 1:1 but there is no observable increase in the fluorescence intensity at the same hIAPP:inhibitor ratio. This was because the fluorescence experiments were performed at a molar ratio of lipid:hIAPP = 150:1, while the ratio used in AFM experiments was 25:1. Lower lipid:hIAPP ratio (or higher concentration of hIAPP at membrane surface) used in the AFM experiments caused more rapid aggregation of hIAPP and thus less effective inhibition for fibril formation. We also measured the AFM image of the inhibitor alone in the presence of phospholipids after the same incubation time (see Figure S1 in the Supporting Information). No any apparent aggregates were observed on the AFM image, confirming that the oligomers appearing in the AFM image of hIAPP in the presence of inhibitor result from the amyloid peptides but not the inhibitor.