1988 Fiscal Year Final Research Report Summary
Matrix Proteins Affecting De Novo Formation of Apatite
| Project/Area Number |
62570821
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Morphological basic dentistry
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| Research Institution | Asahi University, School of Dentistry |
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Principal Investigator |
DOI Yutaka Asahi University, School of Dentistry, 歯学部, 助教授 (40116067)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMOKAWA Hitoyata Tokyo Medical and Dental University, Faculty of Dentistry, 歯学部, 助教授 (80014257)
MORIWAKI Yutaka Asahi University, School of Dentistry, 歯学部, 教授 (90028738)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Osteonectin / Bone Gla Protein / Dentin Phosphoprotein / Calcification / Collagen / Cross-link / Non-Collageneous Proteins / アルカリフオスファターゼ |
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| Research Abstract |
Effects of matrix proteins of bone GLA protein, osteonectin and dentin phosphoprotein on de novo formation of apatite were studied in a wide range of calcium phosphate solutions and in calcium beta-glycerophosphate solutions in the presence of collagen. In every solution, from which amorphous calcium phosphate, octacalcium phosphate, or apatite precipitated as a possible initial phase, each protein at concentrations less than 1muM retarded the precipitation, subsequent transformation to apatite, and ripening crystal growth of apatite. The inhibitory activity increased in the order of osteonectin, bone Gla protein and detin phosphoprotein when compared at the same weight of the protein introduced. In the system employing the calcium beta-glycerophosphate solutions in the presence of catalytic quantity of alkaline phosphatase, it was found that the more the protein inhibitory activity the higher the degree of supersaturation was needed for calcium phosphate to precipitate.
Collagen present as either reconstituted or denatured form had no effect on the protein-added reactions as well as the protein-free reactions and no structural correlation was observed between collagen fibrils and any of the calcium phosphates that appeared in our system. Direct measurement of free calcium levels in the solution suggested that the reduction in calcium activity due to complexing with the protein hardly explained the inhibitory activity of the protein. Instead, TEM observation suggested that the primary mechanism for the protein to inhibit the formation of apatite is to block growth sites of calciu phosphates uncleated. The apatite thus formed in the presence of the more inhibitory protein showed less resolved X-ray diffraction pattems, which accounts for in part smallness of crystal size of apatite formed in the presence of the protein as suggested by TEM.
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