Self-association of calcium and magnesium complexes of dentin phosphophoryn
| Autor: | Mary E. Marsh |
|---|---|
| Rok vydání: | 1989 |
| Předmět: |
Magnesium
Inorganic chemistry Calcium-Binding Proteins chemistry.chemical_element Calcium In Vitro Techniques Phosphate Phosphoproteins Biochemistry Ion Rats Molecular Weight chemistry.chemical_compound Colloid Microscopy Electron Monomer Cross-Linking Reagents chemistry Dentin Animals Saturation (chemistry) Magnesium ion |
| Zdroj: | Biochemistry. 28(1) |
| ISSN: | 0006-2960 |
| Popis: | Self-association of rat dentin phosphophoryn in the presence of calcium and magnesium ions was examined by chemical cross-linking and electron microscopy. Highly phosphorylated phosphophoryn (HP) binds a maximum of 1.33 calcium ions or 1.07 magnesium ions per organic phosphate residue at pH 7.4-8.0. The Ca-HP complexes are predominantly linear when the calcium content of the complex is less than about 65% of the saturation level. At higher calcium levels, the protein has a folded conformation, and transient protein-protein interactions occur. The equilibrium mixture of monomers and oligomers is predominantly monomeric unless the protein is saturated with calcium. The saturated Ca-HP complex forms discrete high molecular weight particles about 25 nm in diameter. The particles are electrically neutral and generally occur in clusters. Mg-HP complexes appear predominantly linear by electron microscopy at all concentrations of bound magnesium up to about 99% of the saturation level; however, protein-protein interaction is measurable when the magnesium content is as little as 65% of the saturation level. At saturation, Mg-HP complexes form high molecular weight particles which are negatively charged. Because of the negative charge, these particles form a stable colloidal suspension and have a rather stellate configuration. |
| Databáze: | OpenAIRE |
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