Phosphatase

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phosphatase

[′fäs·fə‚tās]
(biochemistry)
An enzyme that catalyzes the hydrolysis and synthesis of phosphoric acid esters and the transfer of phosphate groups from phosphoric acid to other compounds.

Phosphatase

 

any of the enzymes of the hydrolase class that catalyze the hydrolysis of phosphoric acid esters in animals, plants, and microorganisms. Phosphatases maintain the phosphate level necessary for various biochemical processes; it may be that they also transport phosphate to the cell.

Depending on the chemical nature of the substrate, phosphatases are divided into monophosphatases, for example, glucose 6-phosphatase, which hydrolyze monoesters of phosphoric acid, and diphosphatases, such as nucleases, which break down the diesters of phosphoric acid. Monophosphatases, in turn, are classified as either specific (interacting with only one substrate) or nonspecific (having a wide range of activity). Depending on the nature of the medium in which their maximum activity is observed, nonspecific monophosphatases are referred to as either alkaline (optimal activity at pH 8–10) or acid (pH 4–6). Alkaline phosphatases are found in animal tissue (intestinal mucosa, placenta, kidneys, bones) and in milk, bacteria, and fungi; acid phosphatases are present in the tissue of the prostate gland, spleen, and liver and in yeasts, bacteria, and higher plants.

The most comprehensive studies have been carried out on the structure and mechanism of activity of the alkaline phosphatase in Escherichia coli. The enzyme is composed of two identical sub-units that function alternately; it contains firmly bonded Zn atoms and has a molecular weight of 80,000. The arrangement of the polypeptide chains is known, and it has been established that the reaction with the substrate passes through a stage of enzyme phosphorylation. A determination of the activity of acid and alkaline phosphatases is important in diagnosing diseases, such as rickets, that are accompanied by an increase in phosphatase activity.

REFERENCES

The Enzymes, 3rd ed., vol. 4. New York-London, 1971.

S. M. AVAEVA

References in periodicals archive ?
These health consequences have led to mortality in up to 24% of women.5 A study in Pakistan identified the risk factors in postmenopausal women who had osteoporotic hip fractures and they identified that advancing age, early menopause, low BMI, longer duration of menopause, smoking, poor socioeconomic conditions, illiteracy, multiparity, lack of calcium supplements, injudicious use of steroids are the important risk factors.6 Alkaline phosphatase (ALP), a homodimeric protein with phosphorylating properties exist in many isozyme forms, the most common of them being tissue non-specific ALP.
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Moss and King [11] reported the greater heat stability of liver phosphatase as compared with bone phosphatase.
Abbreviations CNS: Central nervous system EGFR: Epidermal growth factor receptor ER: Endoplasmic reticulum FAK: Focal adhesion kinase IR: Insulin receptor NLR: NOD-like receptors NO: Nitric oxide NOS: Nitric oxide synthase PDGF: Platelet-derived growth factor PP2: 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo [3, 4-d] pyrimidine PTKs: Protein tyrosine kinases PTPs: Protein tyrosine phosphatases ROS: Reactive oxygen species RTK: Receptor tyrosine kinases.
Tonks, "Protein tyrosine phosphatases: from genes, to function, to disease," Nature Reviews Molecular Cell Biology, vol.
In the late phase of this process, ROS-induced activation of different phosphatases maybe involved in ERK1/2 as well as FAK dephosphorylation, leading to a decrease in HUVECs adhesion.
Intestinal alkaline phosphatase prevents antibiotic-induced susceptibility to enteric pathogens.
Phosphatase inhibitors included 2 mmol [1.sup.-1] sodium orthovanadate, a tyrosine phosphatase, adenosine triphosphatase (ATPase), and a non-specific alkaline phosphatase inhibitor; 20 mmol [1.sup.-1] sodium fluoride, a non-specific acid phosphatase inhibitor; 4 mmol [1.sup.-1] sodium pyrophosphate, an inhibitor of serine and threonine phosphatases; 50 mmol [1.sup.-1] EDTA, which chelates calcium and magnesium essential for phosphatase function; and 250 mmol [1.sup.-1] tetramisole, a specific inhibitor of alkaline phosphatase.
The Src homology 2 domain tyrosine phosphatases SHP-1 and SHP-2: Diversified control of cell growth, inflammation, and injury.
Nitrogen mineral fertilization stimulates phosphatase activity, most likely because phosphatase requires a substantial investment of N (Olander & Vitousek, 2000), and thus, adding N to the soil increases phosphatase activity.
As important drivers of soil ecosystem metabolism, the activity of soil enzymes, such as urease, phosphatase and cellulase, can reflect the strength of soil nutrient mineralisation and energy metabolism (Keeler et al.