Figures S1-S7, HPLC charts for all reaction entries underlying the conversion yields to the products, experimental details, and synthetic protocols (PDF). The atomic coordinate and structure factor of Piv-NFGAIL-NH2 (pNL) have been deposited in the Protein Data Bank () under the accession code 8IMC. The result suggests that the packing structure of the fibrils of pNL is similar to that of the crystal, which also adopted a thin needle-like shape (Fig. ). Therefore, the catalytic mechanism of the amyloid catalyst can be rationally based on the crystal structure, although we cannot rule out a possible difference in the detailed packing structures of fibrils and crystals. (22) Although the amide bond between the pivaloyl group and Asn was oriented along the fiber axis, the distance between O and N in C=O•••H-N between the peptide chains was a little longer (3.2 Å) than the other six amides (2.7-3.0 Å) to form the hydrogen bonds. This is likely due to slight twisting of the amide bond between the pivaloyl group and Asn resulting from the steric hindrance of the pivaloyl group. Thus, the extended hydrogen-bonding distance along the fiber axis in pNL may account for the lower amyloidogenicity compared with NL6.