Enzymatic processing of amelogenin during continuous crystallization of apatite

• Published in: Journal of materials research 2008-12, Vol.23 (12), p.3184-3195
• Main Authors: Uskoković, V., Kim, M-K., Li, W., Habelitz, S.
• Format: Article
• Language: English
• Subjects: Applied and Technical Physics; Biomaterials; Biomimetic (assembly); Ceramic; Inorganic Chemistry; Materials Engineering; Materials Science; Nanotechnology; Nucleation & growth
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/JMR.2008.0387

Dental enamel forms through a protein-controlled mineralization and enzymatic degradation process with a nanoscale precision that new engineering technologies may be able to mimic. Recombinant full-length human amelogenin (rH174) and a matrix-metalloprotease (MMP-20) were used in a pH-stat 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 interaction between rH174 and its proteolytic cleavage products. Despite continuous titration, the levels of calcium exhibited a consistent trend of decreasing, thereby indicating a possible role in protein self-assembly. This study suggests that mimicking enamel formation in vitro requires the synergy between the aspects of matrix self-assembly, proteolysis, and crystallization.