C-terminal amidation of an osteocalcin-derived peptide promotes hydroxyapatite crystallization.
Genesis of natural biocomposite-based materials, such as bone, cartilage, and teeth, involves interactions between organic and inorganic systems. Natural biopolymers, such as peptide motif sequences, can be used as a template to direct the nucleation and crystallization of hydroxyapatite (HA). In this study, a natural motif sequence consisting of 13 amino acids present in the first helix of osteocalcin was selected based on its calcium binding ability and used as substrate for nucleation of HA crystals. The acidic (acidic osteocalcin-derived peptide (OSC)) and amidic (amidic osteocalcin-derived peptide (OSN)) forms of this sequence were synthesized to investigate the effects of different C termini on the process of biomineralization. Electron microscopy analyses show the formation of plate-like HA crystals with random size and shape in the presence of OSN. In contrast, spherical amorphous calcium phosphate is formed in the presence of OSC. Circular dichroism experiments indicate conformational changes of amidic peptide to an open and regular structure as a consequence of interaction with calcium and phosphate. There is no conformational change detectable in OSC. It is concluded that HA crystal formation, which only occurred in OSN, is attributable to C-terminal amidation of a natural peptide derived from osteocalcin. It is also proposed that natural peptides with the ability to promote biomineralization have the potential to be utilized in hard tissue regeneration.
Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran 14115-175, Iran; Tissue Engineering and Biomaterials Division, National Institute of Genetic Engineering and Biotechnology, Tehran 14965/161, Iran.
Samaneh
S
Hosseini
Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran 14115-175, Iran. Electronic address: naderman@modares.ac.ir.
Hossein
H
Naderi-Manesh
Department of Anatomy and Cell Biology, McGill University, Montréal, Quebec H3A 0C7, Canada.
Driss
D
Mountassif
Department of Mining and Materials Engineering, McGill University, Montréal, Quebec H3A 0C7, Canada.
Marta
M
Cerruti
Department of Anatomy and Cell Biology, McGill University, Montréal, Quebec H3A 0C7, Canada; Facility for Electron Microscopy Research, McGill University, Montréal, Quebec H3A 0C7, Canada.
Hojatollah
H
Vali
Tissue Engineering and Biomaterials Division, National Institute of Genetic Engineering and Biotechnology, Tehran 14965/161, Iran. Electronic address: sfaghihi@nigeb.ac.ir.
Shahab
S
Faghihi
D000595:Amino Acid Sequence; D000818:Animals; D001846:Bone Development; D002118:Calcium / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods; D002942:Circular Dichroism; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry*; D006801:Humans; D008854:Microscopy, Electron / Q000379:methods; D008855:Microscopy, Electron, Scanning / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008969:Molecular Sequence Data; D016348:Osseointegration; D015675:Osteocalcin / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry; D019736:Prostheses and Implants; D017434:Protein Structure, Tertiary; D012038:Regeneration
D010455:Peptides; D015675:Osteocalcin; D017886:Durapatite; D002118:Calcium