West China Journal of Stomatology ›› 2021, Vol. 39 ›› Issue (4): 419-424.doi: 10.7518/hxkq.2021.04.007

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Self-assembly and mineralization of full-length human amelogenin and its functional fragments in vitro

Zhong Xiu1,2(), Lai Tingting1, Chen Liang3, Tian Kun1,2()   

  1. 1.School of Stomatology, Southwest Medical University, Luzhou 646000, China
    2.Dept. of Stomatology, Sichuan Academy of Medical Sciences·Sichuan Provincial People's Hospital, Chengdu 610072, China
    3.Zunyi Medical University, Zunyi 563000, China
  • Received:2020-12-10 Revised:2021-05-03 Online:2021-08-01 Published:2021-08-10
  • Contact: Tian Kun E-mail:397279261@qq.com;tiankun78@hotmail.com
  • Supported by:
    Application Foundation Project of Science & Technology Department of Sichuan Province(2018JY0057)

Abstract: Objective

To investigate the dynamic process of the self-assembly behaviors of a full-length human amelogenin (AM) and its functional fragments tyrosine-rich amelogenin peptide (TRAP) and leucine-rich amelogenin peptide(LRAP) in vitro and its role in hydroxyapatite (HA) crystal formation.


The full-length human AM and its functional fragments, TRAP and LRAP, were reassembled and purified in vitro. The protein solution of 100 µg‧mL-1, pH=8, was prepared in Tris-HCl and incubated at room temperature for 1-15 min. Their self-assembly behaviors were observed and compared under a transmission electron microscope (TEM). The full-length AM was added to artificial saliva and incubated for 3 days. A scanning electron microscope (SEM) was used in observing the morphology of the induced new crystals. Then, TARP and LRAP were added. The resulting solution was incubated for 3 days and then observed again.


When pH=8, the full-length human AM and TRAP assembly started spontaneously and formed “nanospheres” after 15 min.The nanospheres formed by TRAP existed independently, with a uniform size but without obvious internal structures. The full-length AM was assembled hierarchically, which formed “nanospheres” and further extended in all directions, formed a chain structure, and then aggregated into a net. The self-assembly behavior of LRAP was not obvious. Proteins mostly existed in the form of monomers without “nanosphere” formation. Only few oligomers were observed. The full-length AM was induced independently for 3 days to form rod-shaped HA crystals. TRAP and LRAP proteins were added, after 3 days the crystal elongation was obvious in the c axis, but the growth in plane A and plane B was poor.


The self-assembly and mineralization behaviors of full-length human AM, TRAP, and LRAP were consistent with the directional growth mechanism of HA crystals in vivo, providing a theoretical basis for the role of the fragments in the growth and maturation of HA crystals.

Key words: human amelogenin, tyrosine-rich amelogenin peptide, leucine-rich amelogenin peptide, self-assembly, mineralization in vitro

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