Amyloid-like aggregates of a plant protein: a case of a sweet-tasting protein, monellin

Abstract

We report here a novel case of amyloid-like aggregation of a plant protein. A sweet-tasting protein, monellin, experiences an irreversible heat denaturation at pH 2.5 and 85°C. Addition of 100 mM NaCl couples this process with protein aggregation. The aggregates were structured as regular fibers with ∼10 nm width and capable of binding to Congo red, similarly to well-known amyloid fibrils. The amyloid-like aggregation process was also successfully monitored with a calorimetric method. This work supports the universality of the amyloid-like aggregation, not restricted to some special categories of protein.