Dentin phosphoprotein, or phosphophoryn, is one of three
proteins
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
formed from
dentin sialophosphoprotein
Dentin sialophosphoprotein is a precursor protein for other proteins found in the teeth. It is produced by cells (odontoblasts) inside the teeth (dental pulp), and in smaller quantities by bone tissues (osteoblasts and osteocytes). It is required ...
and is important in the regulation of
mineralization
Mineralization may refer to:
* Mineralization (biology), when an inorganic substance precipitates in an organic matrix
** Biomineralization, a form of mineralization
** Mineralization of bone, an example of mineralization
** Mineralized tissues are ...
of
dentin
Dentin () (American English) or dentine ( or ) (British English) ( la, substantia eburnea) is a calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth. It is usually covered by ena ...
.
Phosphophoryn is the most
acidic protein ever discovered and has an
isoelectric point
The isoelectric point (pI, pH(I), IEP), is the pH at which a molecule carries no net electrical charge or is electrically neutral in the statistical mean. The standard nomenclature to represent the isoelectric point is pH(I). However, pI is also u ...
of 1. This extreme acidity is achieved by its
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
sequence. Many portions of its chain are repeating -D-S-S- (
aspartic acid
Aspartic acid (symbol Asp or D; the ionic form is known as aspartate), is an α-amino acid that is used in the biosynthesis of proteins. Like all other amino acids, it contains an amino group and a carboxylic acid. Its α-amino group is in the pro ...
-
serine
Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − form un ...
-serine) sequences. In
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
chemistry, net acidity equates to negative charge. Being highly negative, dentin phosphoprotein is able to attract large amounts of
calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...
. ''I
n vitro'' studies also indicate phosphophoryn can initiate
hydroxyapatite
Hydroxyapatite, also called hydroxylapatite (HA), is a naturally occurring mineral form of calcium apatite with the formula Ca5(PO4)3(OH), but it is usually written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two entities. ...
formation.
[Nanci, Antonio. Ten Cate's Oral Histology: Development, Structure, and Function. 7th ed. St. Louis, MO: Mosby Elsevier, 2008. Print.]
References
Teeth
Proteins
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