Structural phosphate
Editor-In-Chief: Henry A. Hoff
Overview
Inside a cell, phosphate may be structural to a nucleic acid such as DNA and RNA or phospholipid. Outside the cell, phosphate may be dissolved in extracellular fluid (ECF) or form structures such as bone and teeth. Bringing phosphate in any form into the cell from a phosphate containing structure or for such a structure and when needed transporting phosphate out of the cell perhaps to a structure is a necessary activity of phosphate homeostasis for that cell.
Introduction
Inorganic phosphate (Pi) (structural phosphate) behaves as a serine phosphate and is not the same as the enzyme-bound phosphate (catalytic phosphate) derived from ATP during a catalytic reaction.[1]
Catalytic phosphate
Inorganic phosphate (Pi) (structural phosphate) behaves as a serine phosphate and is not the same as the enzyme-bound phosphate (catalytic phosphate) derived from ATP during a lyase reaction of EC 4.1.3.8.[1] Evidence indicates that EC 4.1.3.8 contains one structural phosphate for each catalytic phosphate, which does not affect its catalytic activity.[1]
Phospholipid
Nucleic acid
Cartilage
Teeth
Hydroxyapatite, which is a crystalline calcium phosphate is the primary mineral of enamel.[2]
By weight, seventy percent of dentin consists of the mineral, hydroxylapatite, twenty percent is organic material, and ten percent is water.[3]
Cementum is a specialized bony substance covering the root of a tooth, composed of approximately 45% inorganic material (mainly hydroxyapatite), 33% organic material (mainly collagen) and 22% water.
Bone
During bone resorption high levels of phosphate are released into the ECF as osteoclasts tunnel into mineralized bone, breaking it down and releasing phosphate, that results in a transfer of phosphate from bone fluid to the blood. During childhood, bone formation exceeds resorption, but as the aging process occurs, resorption exceeds formation.
Transphosphorylation between nucleotides and hydroxyapatite (HA) results in a pyrophosphate on HA that is distinctive from pyrophosphate absorbed onto HA from solution. This may be due to a different orientation of the pyrophosphate on the surface depending on the origin of the pyrophosphate.[4]
References
- ↑ 1.0 1.1 1.2 Linn TC, Srere PA (1979). "Identification of ATP citrate lyase as a phosphoprotein". J Biol Chem. 254 (5): 1691–8. PMID 762167. Unknown parameter
|month=ignored (help) - ↑ Johnson, Clarke (1998). "Biology of the Human Dentition".
- ↑ Cate, A.R. Ten. (1998). Oral Histology: development, structure, and function (5th ed.). pp. 150–5. ISBN 0-8151-2952-1.
- ↑ Taves DR, Reedy RC (1969). "A structural basis for the transphosphorylation of nucleotides with hydroxyapatite". Calcified Tissue International. 3 (1): 284–92. doi:10.1007/BF02058670. Unknown parameter
|month=ignored (help)