Key Information
Abstract
Enzyme catalysis is essential for molecular transformations. Here, we make use of amyloid, a fibrillar aggregate formed by stacking peptides with β-sheet, which offers unique selectivity in enzymatic reactions. Azo-stilbene derivative (ASB), the amyloid-recognition motif, is incorporated into the substrate, which allows the amyloid consisting of Bz-Phe-Phe-Ala-Ala-Leu-Leu-NH2 (BL7) to shield the substrates from the approaching enzyme. X-ray crystallographic analysis and structure-shielding effect relationship studies of BL7 reveal that the benzene rings present in the N-terminal benzoyl group and Phe1 side chain are particularly important for the shielding effect on the substrate. The finding results in a selective transformation system in which the reactive site close to ASB is protected by amyloid, while a site far from ASB is converted by the enzymes (trypsin, protein arginine deiminase [PAD], and Staphylococcus aureus V-8 Protease [Glu-C]). Further, the amyloid-shielded enzyme catalysis is compatible with an intact peptide, as the side chain of Tyr can be converted to the amyloid-recognizing motif. The enzymatic reactions combining amyloid provide unique selectivity for molecular transformation which may be used in diverse fields, including in synthetic chemistry.
Subject terms: Peptides, Synthetic chemistry methodology, Biocatalysis
Enzyme catalysis is essential for molecular transformations. Here, the authors show that incorporation of an amyloid recognition motif (azo-stilbene derivative) into the substrate allows the amyloid consisting of Bz-Phe-Phe-Ala-Ala-Leu-Leu-NH2 to shield the substrate from the approaching enzyme.
Introduction
Naturally-occurring enzymes efficiently, precisely, and sustainably catalyze chemical reactions in living organisms. Artificial manipulations, such as genetic engineering of the primary structure and combination with artificial small molecules, have markedly expanded the repertoire of applicable substrates and reaction patterns1external link, opens in a new tab–3external link, opens in a new tab. These enzymatic reactions are currently indispensable in a variety of fields, including in synthetic chemistry. For example, many complex molecule syntheses4external link, opens in a new tab–6external link, opens in a new tab, environmentally-friendly syntheses7external link, opens in a new tab,8external link, opens in a new tab, and cost-effective industrial syntheses9external link, opens in a new tab–11external link, opens in a new tab have been achieved by combination with the enzymatic reactions. However, expanding the scope of enzyme catalysis remains an important challenge.
To date, such artificial interventions have focused on the enzyme. Here, we report a substrate “add-on” strategy to expand the scope of the enzyme reactions (Fig. 1aexternal link, opens in a new tab vs. bexternal link, opens in a new tab). Specifically, the structure as an add-on shields the substrate from the proximity of the enzyme. Amyloids, which have a rigid higher-order structure composed of β-sheet peptides12external link, opens in a new tab, could be one such add-on structure. Here, we demonstrate that amyloid-shielded substrates are no longer under the control of the enzymes (Fig. 1b–1external link, opens in a new tab). In addition, we report the enzymatic reactions combining amyloid enabled regioselective conversion of the substrates, which was previously difficult to achieve (Fig. 1b−2external link, opens in a new tab).