Abstract
This study using Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) was undertaken to further elucidate the sequential alterations of amelogenin conformation and morphology in the process of protein aggregation. Porcine 148-residue amelogenin (called hereafter the 20 kDa amelogenin), which is the major matrix constituent in pig secretory enamel, was used as a model molecule. The results verified that the protein molecules in a monomeric state at 0°C have multiple conformational elements, whereas most of the structural elements become indiscernible in the progression of protein aggregation, except for the β-strand presumed to exist at the N-terminal region. The observations by AFM confirmed that the self-assembly process of the protein in aqueous milieu generates semispherical structures of around 20-30nm in diameter. The overall results support the theory that the programmed extracellular processing of amelogenins is directly mediated by the conserved primary structure and the resulting supramolecular aggregates.
