Enzymatic processing of amelogenin during continuous crystallization of apatite

Abstract

Dental enamel forms through a protein-controlled mineralization and enzymatic degradation with a nanoscale precision that new engineering technologies may be able to mimic. Recombinant fulllength human amelogenin (rH174) and a matrix-metalloprotease (MMP-20) were employed in a pHstat titration system that enabled a continuous supply of calcium and phosphate ions over several days, mimicking the initial stages of matrix processing and crystallization in enamel in-vitro. Effects on the self-assembly and crystal growth from a saturated aqueous solution containing 0.4 mg/ml rH174 and MMP-20 with the weight ratio of 1:1000 with respect to rH174 were investigated. A transition from nanospheres to fibrous amelogenin assemblies was facilitated under conditions that involved an interaction between rH174 and the proteolytic cleavage products. Despite continuous titration, the levels of calcium exhibited a consistent trend of decreasing, thereby indicating its possible role in the protein self-assembly. This study suggests that mimicking enamel formation invitro requires the synergy between the aspects of matrix self-assembly, proteolysis and crystallization.

Amelogenin as a promoter of nucleation and crystal growth of apatite

“…The experimental setting applied in this study was modified from a previous one [13], and is displayed in Fig. 2.…”

Nanosized hydroxyapatite and other calcium phosphates: Chemistry of formation and application as drug and gene delivery agents

“…Such is the case for the current model of amelogenesis wherein nanospherical particles of amelogenin are assumed to bind onto (hk0) faces of the growing HAP crystals and thus foster their uniaxial growth along [001] axis. 91 However, one of the opposing actual explanatory trends lies in invoking the surface-controlled channeling or the diffusion-controlled transportation activity of additives for the sake of building apatite crystals using either amorphous units or individual ions and complexes as building blocks. Such an idea is supported by the successful synthesis of a few ceramic materials, previously obtainable only through high-temperature annealing treatments, by precipitation at room temperature in the presence of short peptides derived from phage display libraries.…”

Zeta-potential and Particle Size Analysis of Human Amelogenins

“…Self-assembly of this protein matrix, 90% of which is initially composed of various amelogenins, is expected to play a crucial role in the proper morphogenesis of this tissue. Understanding the physical and chemical conditions that govern the physiologically relevant self-assembly of amelogenin proteins may thus be an essential step in replicating this complex biological process in vitro and producing artificial structures that resemble enamel (Habelitz et al, 2004(Habelitz et al, , 2005Uskoković et al, 2008).…”