scholarly journals The dephosphorylation of inositol 1,4-bisphosphate to inositol in liver and brain involves two distinct Li+-sensitive enzymes and proceeds via inositol 4-phosphate

1988 ◽  
Vol 249 (1) ◽  
pp. 143-148 ◽  
Author(s):  
C I Ragan ◽  
K J Watling ◽  
N S Gee ◽  
S Aspley ◽  
R G Jackson ◽  
...  
Keyword(s):  
Phosphatase Activity ◽  
Soluble Fraction ◽  
Inositol 1 ◽  
Hydrolysis Of

1. Hydrolysis of both enantiomers of inositol 1-phosphate and both enantiomers of inositol 4-phosphate to inositol is inhibited by LiCl in liver and brain. 2. The phosphatase activity is predominantly soluble. 3. Inositol 1,4-bisphosphate is also hydrolysed by the soluble fraction of liver and brain. 4. Bisphosphatase activity is inhibited by LiCl, but is less sensitive than monophosphatase activity. 5. The product of bisphosphatase in liver and brain is inositol 4-phosphate.

scholarly journals The dephosphorylation pathway of d-myo-inositol 1,3,4,5-tetrakisphosphate in rat brain

1987 ◽  
Vol 247 (3) ◽  
pp. 635-639 ◽  
Author(s):  
C Erneux ◽  
A Delvaux ◽  
C Moreau ◽  
J E Dumont
Keyword(s):  
Rat Brain ◽  
Soluble Fraction ◽  
Deae Cellulose ◽  
Phosphatase Activities ◽  
Inositol 1 ◽  
The Third ◽  
Inositol 1,4,5 Trisphosphate ◽  
Hydrolysis Of ◽  
Blue Sepharose

Dephosphorylation of inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] was measured in both the soluble and the particulate fractions of rat brain homogenates. Analysis of the hydrolysis of [4,5-32P]Ins(1,3,4,5)P4 showed that for both fractions the 5-phosphate of Ins(1,3,4,5)P4 was removed and inositol 1,3,4-trisphosphate [Ins(1,3,4)P3] was specifically produced. In the soluble fraction, Ins(1,3,4)P3 was further hydrolysed at the 1-phosphate position to inositol 3,4-bisphosphate[Ins(3,4)P2]. DEAE-cellulose chromatography of the soluble fraction separated the phosphatase activities into three peaks. The first hydrolysed both Ins(1,3,4,5)P4 and inositol 1,4,5-trisphosphate, the second inositol 1-phosphate and the third Ins(1,3,4)P3 and inositol 1,4-bisphosphate, [Ins(1,4)P2]. Further purification of the third peak on either Sephacryl S-200 or Blue Sepharose could not dissociate these two activities [i.e. with Ins(1,4)P2 and Ins(1,3,4)P3 as substrates]. The dephosphorylation of Ins(1,3,4)P3 could be inhibited by the addition of Li+.

scholarly journals Insulin-receptor phosphotyrosyl-protein phosphatases

1988 ◽  
Vol 256 (3) ◽  
pp. 893-902 ◽  
Author(s):  
M J King ◽  
G J Sale
Keyword(s):  
Insulin Receptor ◽  
Phosphatase Activity ◽  
Rat Liver ◽  
Protein Phosphatase ◽  
Egf Receptor ◽  
Soluble Fraction ◽  
Protein Phosphatases ◽  
Egf Receptors ◽  
Cell Extracts ◽  
Dependent Protein

Calmodulin-dependent protein phosphatase has been proposed to be an important phosphotyrosyl-protein phosphatase. The ability of the enzyme to attack autophosphorylated insulin receptor was examined and compared with the known ability of the enzyme to act on autophosphorylated epidermal-growth-factor (EGF) receptor. Purified calmodulin-dependent protein phosphatase was shown to catalyse the complete dephosphorylation of phosphotyrosyl-(insulin receptor). When compared at similar concentrations, 32P-labelled EGF receptor was dephosphorylated at greater than 3 times the rate of 32P-labelled insulin receptor; both dephosphorylations exhibited similar dependence on metal ions and calmodulin. Native phosphotyrosyl-protein phosphatases in cell extracts were also characterized. With rat liver, heart or brain, most (75%) of the native phosphatase activity against both 32P-labelled insulin and EGF receptors was recovered in the particulate fraction of the cell, with only 25% in the soluble fraction. This subcellular distribution contrasts with results of previous studies using artificial substrates, which found most of the phosphotyrosyl-protein phosphatase activity in the soluble fraction of the cell. Properties of particulate and soluble phosphatase activity against 32P-labelled insulin and EGF receptors are reported. The contribution of calmodulin-dependent protein phosphatase activity to phosphotyrosyl-protein phosphatase activity in cell fractions was determined by utilizing the unique metal-ion dependence of calmodulin-dependent protein phosphatase. Whereas Ni2+ (1 mM) markedly activated the calmodulin-dependent protein phosphatase, it was found to inhibit potently both particulate and soluble phosphotyrosyl-protein phosphatase activity. In fractions from rat liver, brain and heart, total phosphotyrosyl-protein phosphatase activity against both 32P-labelled receptors was inhibited by 99.5 +/- 6% (mean +/- S.E.M., 30 observations) by Ni2+. Results of Ni2+ inhibition studies were confirmed by other methods. It is concluded that in cell extracts phosphotyrosyl-protein phosphatases other than calmodulin-dependent protein phosphatase are the major phosphotyrosyl-(insulin receptor) and -(EGF receptor) phosphatases.

scholarly journals Zinc-Ion-Dependent Acid Phosphatase Exhibits Magnesium-Ion-Dependent myo-Inositol-1-phosphatase Activity.

1996 ◽  
Vol 19 (6) ◽  
pp. 882-885 ◽  
Author(s):  
Sadaki FUJIMOTO ◽  
Isako OKANO ◽  
Yutaka TANAKA ◽  
Yasuo SUMIDA ◽  
Jyunji TSUDA ◽  
...  
Keyword(s):  
Acid Phosphatase ◽  
Phosphatase Activity ◽  
Zinc Ion ◽  
Magnesium Ion ◽  
Inositol 1

scholarly journals The dynamics of acid-soluble phosphorus compounds in the course of winter and spring wheat germination under various thermic conditions. Part II. Labile phosphorus after hydrolysis of the acid-soluble fraction

2015 ◽  
Vol 24 (2) ◽  
pp. 297-308
Author(s):  
A. Barbaro
Keyword(s):  
Low Temperature ◽  
Phosphorus Content ◽  
Soluble Fraction ◽  
Phosphorus Compounds ◽  
Labile Phosphorus ◽  
Soluble Phosphorus ◽  
Germination Temperature ◽  
Wheat Germination ◽  
Labile P ◽  
Hydrolysis Of

The changes in labile phosphorus compounds content during germination of wheat were investigated. These compounds were determined in acid-soluble germ extracts separated into fractions according to the solubility of their barium salts. Low germination temperature was found to raise the labile phosphorus content in the fraction of insoluble barium salts. If we assume that labile P of this fraction consisted mainly of adenosinedi- and triphosphates, it would seem that the rise, in the ATP and ADP level under the influence of low temperature may be essential for initiating flowering in winter varieties.

A phenoxo-bridged dicopper(ii) complex as a model for phosphatase activity: mechanistic insights from a combined experimental and computational study

2017 ◽  
Vol 46 (12) ◽  
pp. 4038-4054 ◽  
Author(s):  
Suman K. Barman ◽  
Totan Mondal ◽  
Debasis Koley ◽  
Francesc Lloret ◽  
Rabindranath Mukherjee
Keyword(s):  
Dft Calculations ◽  
Phosphatase Activity ◽  
Theoretical Approach ◽  
Computational Study ◽  
Hydrolysis Of

Hydrolysis of RNA-model substrate HPNP by a dicopper(ii) complex has been studied with combined experimental and theoretical approach. Involvement of H-bonding has been probed by DFT calculations.

scholarly journals Accumulation of inositol polyphosphate isomers in agonist-stimulated cerebral-cortex slices. Comparison with metabolic profiles in cell-free preparations

1989 ◽  
Vol 258 (1) ◽  
pp. 23-32 ◽  
Author(s):  
I H Batty ◽  
A J Letcher ◽  
S R Nahorski
Keyword(s):  
Cerebral Cortex ◽  
Inositol Phosphates ◽  
Periodate Oxidation ◽  
Chemical Degradation ◽  
Inositol Polyphosphate ◽  
Tissue Slices ◽  
Inositol 1 ◽  
Agonist Stimulation ◽  
Cortex Slices ◽  
Hydrolysis Of

1. Basal and carbachol-stimulated accumulations of isomeric [3H]inositol mono-, bis-, tris- and tetrakis-phosphates were examined in rat cerebral-cortex slices labelled with myo-[2-3H]inositol. 2. In control samples the major [3H]inositol phosphates detected were co-eluted on h.p.l.c. with Ins(1)P, Ins(4)P (inositol 1- and 4-monophosphate respectively), Ins(1,4)P2 (inositol 1,4-bisphosphate), Ins(1,4,5)P3 (inositol 1,4,5-tris-phosphate) and Ins(1,3,4,5)P4 (inositol 1,3,4,5-tetrakisphosphate). 3. After stimulation to steady state with carbachol, accumulation of each of these products was markedly increased. 4. Agonist stimulation, however, also evoked much more dramatic increased accumulations of a second [3H]inositol trisphosphate, which was co-eluted on h.p.l.c. with authentic Ins(1,3,4)P3 (inositol 1,3,4-trisphosphate) and of three further [3H]inositol bisphosphates ([3H]InsP2(s]. 5. Examination of the latter by chemical degradation by periodate oxidation and/or h.p.l.c. allowed identification of these as [3H]Ins(1,3)P2, [3H]Ins(3,4)P2 and [3H]Ins(4,5)P2 (inositol 1,3-, 3,4- and 4,5-bisphosphates respectively), which respectively accounted for about 22%, 8% and 3% of total [3H]InsP2 in extracts from stimulated tissue slices. 6. By using a h.p.l.c. method which clearly resolves Ins(1,3,4,5)P4 and Ins(1,3,4,6)P4 (inositol 1,3,4,6-tetrakisphosphate), only the former isomer could be detected in extracts from either control or stimulated tissue slices. Similarly, [3H]inositol pentakis- and hexakis-phosphates were not detectable either in the presence or absence of carbachol under the radiolabelling conditions described. 7. The catabolism of [3H]Ins(1,4,5)P3 and [3H]Ins(1,3,4)P3 by cell-free preparations from cerebral cortex was also studied. 8. In the presence of Mg2+, [3H]Ins(1,4,5)P3 was specifically dephosphorylated via [3H]Ins(1,4)P2 and [3H]Ins(4)P to free [3H]inositol, whereas [3H]Ins(1,3,4)P3 was degraded via [3H]Ins(3,4)P2 and, to a lesser extent, via [3H]Ins(1,3)P2 to D- and/or L-[3H]Ins(1)P and [3H]inositol. 9. In the presence of EDTA, hydrolysis of [3H]Ins(1,4,5)P3 was greater than or equal to 95% inhibited, whereas [3H]Ins(1,3,4)P3 was still degraded, but yielded only a single [3H]InsP2 identified as [3H]Ins(1,3)P2. 10. The significance of these observations with cell-free preparations is discussed in relation to the proportions of the separate isomeric [3H]inositol phosphates measured in stimulated tissue slices.

Enantioselective hydrolysis of epoxides: the employment of the soluble fraction from Vicia sativa seedlings

2001 ◽  
Vol 14 (4-6) ◽  
pp. 125-129
Author(s):  
Cinzia Chiappe ◽  
Antonietta De Rubertis ◽  
Franco Marioni ◽  
Filippo Pelagotti
Keyword(s):  
Soluble Fraction ◽  
Enantioselective Hydrolysis ◽  
Vicia Sativa ◽  
Hydrolysis Of

scholarly journals Phosphomonoesterase hydrolysis of polyphosphoinositides in rat kidney: Properties and subcellular localization of the enzyme system

1975 ◽  
Vol 150 (3) ◽  
pp. 537-551 ◽  
Author(s):  
P H Cooper ◽  
J N Hawthorne
Keyword(s):  
Phosphatase Activity ◽  
Metal Ion ◽  
Rat Kidney ◽  
Gradient Centrifugation ◽  
Sodium Deoxycholate ◽  
Subcellular Fractionation ◽  
Kidney Cortex ◽  
Ph Optimum ◽  
Triton X ◽  
Hydrolysis Of

Tthe properties of diphosphoinositide and triphosphoinositide phosphatases from rat kidney homogenate were studied in an assay system in which non-specific phosphatase activity was eliminated. The enzymes were not completely metal-ion dependent and were activated by Mg2+. The detergent sodium deoxycholate, Triton X-100 and Cutscum inhibited the reaction; cetyltrimethylammonium bromide only activated when added with the subtrates and in the presence Mg2+. Both enzymes had a pH optimum of 7.5. Ca2+ and Li+ both activated triphosphoinositide phosphatase, but Ca2+ inhibited and L+ had little effect on diphosphoinositide phosphatase. Cyclic AMP had no effect on either enzyme. The enzymes were three times more active in kidney cortex than in the medulla. On subcellular fractionation of kidney-cortex homogenates by differential and density-gradient centrifugation, the distribution of the enzymes resembled that of thiamin pyrophosphatase (assayed in the absence of ATP), suggesting localization in the Golgi complex. However, the distribution differed from that of the liver Golgimarker galactosyltransferase. Activities of both diphosphoinositide and triphosphoinositide phosphatases and thiamin pyrophosphatase were low in purified brush-border fragments. Further experiments indicate that at least part of the phosphatase activity is soluble.

scholarly journals A Comparison of Human Leukocyte Phosphatase Activity toward Sodium β-Glycerophosphate, Adenosine 5'-Phosphate and Glucose 1-Phosphate

Blood ◽  
1959 ◽  
Vol 14 (4) ◽  
pp. 415-422 ◽  
Author(s):  
JAMES H. FOLLETTE ◽  
WILLIAM N. VALENTINE ◽  
JOHN REYNOLDS
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Cell Population ◽  
Alkaline Phosphatase Activity ◽  
Human Leukocyte ◽  
Maximal Activity ◽  
Phosphate Esters ◽  
Chronic Myelocytic Leukemia ◽  
Myelocytic Leukemia ◽  
Hydrolysis Of

Abstract The ability of human leukocyte enzymes to hydrolyze phosphorus is compared in terms of the conventional substrate sodium β-glycerophosphate and the metabolically important phosphate esters, adenosine 5'-phosphate and glucose 1-phosphate. At pH 9.9, there is marked and comparable variation in phosphatase activity toward all three substrates, this being low in chronic myelocytic leukemia and high in the presence of infection and certain "stressful" states. Moreover, substrate mixture experiments show no increased hydrolysis of phosphorus when two substrates are present in the incubation mixture. Increased phosphatase activity toward both glucose 1-phosphate and sodium β-glycerophosphate resulted when corticosteroids were administered in large doses for 72 hours. The data, while not providing absolute proof, are compatible with the hydrolysis of phosphorus at pH 9.9, being due in the case of all three substrates to the activity of the same phosphomonoesterase or group of phosphomonesterases. At pH 5.5, phosphatase activity toward both sodium β-glycerophosphate and adenosine 5'-phosphate was likewise demonstrated, but, in leukocytes, the pH of maximal activity varies from subject to subject and is dependent to a large extent on the amount of the highly variable "alkaline phosphatase" activity present in any given cell population at the time of analysis.

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