scholarly journals Inhibition of human alkaline phosphatases by vanadate

1979 ◽  
Vol 181 (1) ◽  
pp. 247-250 ◽  
Author(s):  
L E Seargeant ◽  
R A Stinson
Keyword(s):  
Alkaline Phosphatase ◽  
Binding Site ◽  
Human Liver ◽  
Competitive Inhibitor ◽  
Enzymic Activity ◽  
Alkaline Phosphatases

Orthovanadate was shown to be a potent competitive inhibitor (Ki less than 1 microM) of purified alkaline phosphatase from human liver, intestine of kidney. Inhibition was reversed and full enzymic activity restored in the presence of 1mM-adrenaline. Phosphate and vanadate competed for the same binding site on the enzyme.

Alkaline phosphatase. I. Kinetics and inhibition by levamisole of purified isoenzymes from humans.

1976 ◽  
Vol 22 (7) ◽  
pp. 972-976 ◽  
Author(s):  
H Van Belle
Keyword(s):  
Alkaline Phosphatase ◽  
Substrate Concentration ◽  
Human Liver ◽  
Alkaline Phosphatases ◽  
Mechanism Of Inhibition ◽  
Optimum Ph ◽  
Alkaline Phosphatase Isoenzymes

Abstract I studied the kinetics and sensitivity toward inhibition by levamisole and R 8231 of the most important human alkaline phosphatase isoenzymes. N-Ethylaminoethanol proved superior to the now widely used diethanolamine buffer, especially for the enzymes from the intestine and placenta, behaving as an uncompetitive activator. The optimum pH largely depends on the substrate concentration. The addition of Mg2+ has no effect on the activities. The meaning of Km-values for alkaline phosphatases is questioned. Isoenzymes from human liver, bone, kidney, and spleen are strongly inhibited by levamisole or R 8231 at concentrations that barely affect the enzymes from intestine or placenta. The inhibition is stereospecific, uncompetitive, and not changed by Mg2+. Inhibition is counteracted by increasing concentrations of N-ethylaminoethanol. The mechanism of inhibition is suggested to be formation of a complex with the phosphoenzyme.

Incorporation of human liver and placental alkaline phosphatases into liposomes and membranes is via phosphatidylinositol

1990 ◽  
Vol 68 (9) ◽  
pp. 1112-1118 ◽  
Author(s):  
Lee Kihn ◽  
Dorothy Rutkowski ◽  
Robert A. Stinson
Keyword(s):  
Alkaline Phosphatase ◽  
Phospholipase C ◽  
Human Liver ◽  
Red Cell ◽  
Osteosarcoma Cells ◽  
Alkaline Phosphatases ◽  
Membrane Anchor ◽  
Gradient Gel Electrophoresis ◽  
Triton X ◽  
Phosphatidylinositol Phospholipase C

As assessed by incorporation into liposomes and by adsorption to octyl-Sepharose, the integrity of the membrane anchor for the purified tetrameric forms of alkaline phosphatase from human liver and placenta was intact. Any treatment that resulted in a dimeric enzyme precluded incorporation and adsorption. An intact anchor also allowed incorporation into red cell ghosts. The addition of hydrophobic proteins inhibited incorporation into liposomes to varying degrees. Alkaline phosphatase was 100% releasable from liposomes and red cell ghosts by a phospholipase C specific for phosphatidylinositol. There was no appreciable difference in the rates of release of placental and liver alkaline phosphatases, although both were approximately 250 × slower in liposomes and 100 × slower in red cell ghosts than the enzyme's release from a suspension of cultured osteosarcoma cells. Both enzymes were released by phosphatidylinositol phospholipase C as dimers and would not reincorporate or adsorb to octyl-Sepharose. However, the enzyme incorporated, resolubilized by Triton X-100, and cleansed of the detergent by butanol treatment was tetrameric by gradient gel electrophoresis, was hydrophobic, and could reincorporate into fresh liposomes. A monoclonal antibody to liver alkaline phosphatase inhibited the enzyme's incorporation into liposomes, and abolished its release from liposomes and its conversion to dimers by phosphatidylinositol phospholipase C.Key words: alkaline phosphatase, liposome, phosphatidylinositol, membrane anchor.

scholarly journals Isoelectric focusing of human liver alkaline phosphatase

1970 ◽  
Vol 118 (2) ◽  
pp. 299-302 ◽  
Author(s):  
A. L. Latner ◽  
Mary E. Parsons ◽  
A. W. Skillen
Keyword(s):  
Alkaline Phosphatase ◽  
Density Gradient ◽  
Isoelectric Focusing ◽  
Isoelectric Point ◽  
Human Liver ◽  
Sucrose Density Gradient ◽  
Ph Gradient ◽  
Alkaline Phosphatases ◽  
Carrier Ampholytes

1. Isoelectric focusing of human liver alkaline phosphatase in a sucrose density gradient with LKB Ampholine as carrier ampholytes is described. 2. Problems due to the chelating properties of the ampholytes and the pH gradient were examined. 3. A reactivation procedure to counter these effects was devised that can probably be used for other alkaline phosphatases. 4. The isoelectric point of human liver alkaline phosphatase was found to be pH3.9.

scholarly journals The influence of metal ions on the orthophosphatase and inorganic pyrophosphatase activities of human alkaline phosphatase

1969 ◽  
Vol 112 (5) ◽  
pp. 699-701 ◽  
Author(s):  
D W Moss
Keyword(s):  
Alkaline Phosphatase ◽  
Metal Ions ◽  
Competitive Inhibitor ◽  
Inorganic Pyrophosphatase ◽  
Intestinal Alkaline Phosphatase ◽  
Alkaline Phosphatases ◽  
Low Concentrations ◽  
Pyrophosphatase Activity ◽  
Hydrolysis Of ◽  
Pyrophosphate Hydrolysis

1. The differential effects of adding Zn2+ and Mg2+ on the orthophosphatase and inorganic pyrophosphatase activities of human intestinal alkaline phosphatase were studied. 2. In the presence of excess of Zn2+, inorganic pyrophosphatase activity is inhibited. At higher concentrations of pyrophosphate, hydrolysis of this substrate takes place, but is inhibited competitively by the Zn2+–pyrophosphate complex. This complex also acts as a competitive inhibitor of orthophosphate hydrolysis. 3. Excess of Mg2+ also inhibits pyrophosphatase action by removal of substrate; at low concentrations, this ion activates pyrophosphatase, as is the case with orthophosphatase. 4. It is concluded that, when interactions between metal ions and pyrophosphate are taken into account, the effects of these ions are consistent with the view that alkaline phosphatases possess both orthophosphatase and inorganic pyrophosphatase activities.

scholarly journals Partial purification and kinetics of oestriol 16α-glucuronyltransferase from the cytosol fraction of human liver

1970 ◽  
Vol 118 (4) ◽  
pp. 625-634 ◽  
Author(s):  
Govind S. Rao ◽  
Marie Luise Rao ◽  
Heinz Breuer
Keyword(s):  
Human Liver ◽  
Glucuronic Acid ◽  
Specific Radioactivity ◽  
Competitive Inhibitor ◽  
Enzymic Activity ◽  
Hydroxyl Group ◽  
Partial Purification ◽  
Cytosol Fraction ◽  
Enzyme Substrate ◽  
Kinetics Of

An enzyme that conjugates the 16α-hydroxyl group of oestriol with glucuronic acid was found in the cytosol fraction of human liver. The enzymic activity could not be sedimented when the cytosol fraction was centrifuged at 158000gav. for 120min. The oestriol 16α-glucuronyltransferase was purified 100-fold by 0–30% saturation of the cytosol fraction with ammonium sulphate followed by filtration of the precipitate through Sephadex G-200. The activity was eluted at the void volume. The product of the reaction, oestriol 16α-monoglucuronide, was identified by paper chromatography and by crystallization of radioactive product to constant specific radioactivity. The optimum temperature was 37°C, and the activation energy was calculated to be 11.1kcal/mol. The apparent Michaelis–Menten constants for oestriol and UDP-glucuronic acid were 13.3 and 100μm respectively. Cu2+, Zn2+ and Hg2+ inhibited, whereas Mg2+, Mn2+ and Fe2+ stimulated the enzyme. Substrate-specificity studies indicated that the amount of oestradiol-17β, oestradiol-17α and oestrone conjugated was not more than about 5% of that found for oestriol. Oestriol 16α-monoglucuronide, a product of the reaction, did not inhibit the 16α-oestriol glucuronyltransferase; in contrast, UDP, another product of the reaction, inhibited the enzyme competitively with respect to UDP-glucuronic acid as the substrate, and non-competitively with respect to oestriol as the substrate. ATP and UDP-N-acetylglucosamine did not affect the oestriol 16α-glucuronyltransferase. 17-Epioestriol acted as a competitive inhibitor and 16-epioestriol as a non-competitive inhibitor of the glucuronidation of oestriol. 5α-Pregnane-3α,20α-diol also inhibited the enzyme non-competitively. It is most likely that the oestriol 16α-glucuronyltransferase described here is bound to the membranes of the endoplasmic reticulum.

Soil response to chemicals used in a field experiment

2013 ◽  
Vol 27 (2) ◽  
pp. 151-158 ◽  
Author(s):  
S. Jezierska-Tys ◽  
A. Rutkowska
Keyword(s):  
Alkaline Phosphatase ◽  
Enzymatic Activity ◽  
Field Experiment ◽  
Soil Microorganisms ◽  
Block Design ◽  
Soil Samples ◽  
Alkaline Phosphatases ◽  
Soil Response ◽  
Negative Effect ◽  
Set Up

Abstract The effect of chemicals (Reglone 200 SL and Elastiq 550 EC) on soil microorganisms and their enzymatic activity was estimated. The study was conducted in a field experiment which was set up in the split-block design and comprised three treatments. Soil samples were taken six times, twice in each year of study. The results showed that the application of chemicals generally had no negative effect on the number of soil microorganisms. The application of Reglone 200 SL caused an increase of proteolytic and ureolytic activity and affected the activity of dehydrogenases, acid and alkaline phosphatases in the soil. The soil subjected of Elastiq 550 EC was characterized by lower activity of dehydrogenases, protease, urease and alkaline phosphatase.

Endothelial and Bile Canalicular Alkaline Phosphatase in Human Liver and Serum

1976 ◽  
Vol 36 (2) ◽  
pp. 131-135 ◽  
Author(s):  
Inga Hägerstrand ◽  
Karin Lindholm ◽  
Ylva Lindroth
Keyword(s):  
Alkaline Phosphatase ◽  
Human Liver

Effects of Kanwa on Rat Gastrointestinal Phosphatases

2010 ◽  
Vol 3 (3) ◽  
pp. 1147-1152
Author(s):  
Jacob Bamaiyi ◽  
Omajali ◽  
Sanni Momoh
Keyword(s):  
Alkaline Phosphatase ◽  
Small Intestine ◽  
Acid Phosphatase ◽  
Sodium Carbonate ◽  
Elevated Level ◽  
Food Additive ◽  
Alkaline Phosphatases ◽  
Acid And Alkaline Phosphatases ◽  
Diagnostic Indices ◽  
High Level

This study investigates the effects of kanwa on rat gastrointestinal phosphatases. The rats were administered 7% w/v concentration of  trona (Kanwa) orally for a period of two weeks in order to investigate how this compound is being used as food additive in some homes in Nigeria. The Kanwa used in this study was the handpicked variety obtained from sellers from Anyigba market in eastern part of Kogi State, Nigeria. Kanwa, a hydrated sodium carbonate (Na2CO3NaHCO3.2H2O) was obtained as a dried lake salt. Acid phosphatase has the ability to dephosphorylate molecules containing phosphate group. The decreased and elevated level in serum or plasma acid and alkaline phosphatases serves as diagnostic indices for various diseases. Results showed that there was increase and decrease of acid phosphatase (ACP) activities in both the stomach and small intestine. The activities of alkaline phosphatase (ALP) fluctuated in the small intestine. However, in the stomach, an increase activity of ALP was noticed throughout the period of ‘Kanwa’ administration. We concluded that although the level of ‘Kanwa’ consumed in most homes may not be toxic if not taken continuously or repeatedly. Thus, continuous consumption should be discouraged as accumulation of high level of ‘Kanwa’ may cause damages or injuries to the various organs/tissues and may disrupt normal body function.

scholarly journals Study of Endogen Substrates, Drug Substrates and Inhibitors Binding Conformations on MRP4 and Its Variants by Molecular Docking and Molecular Dynamics

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1051
Author(s):  
Edgardo Becerra ◽  
Giovanny Aguilera-Durán ◽  
Laura Berumen ◽  
Antonio Romo-Mancillas ◽  
Guadalupe García-Alcocer
Keyword(s):  
Molecular Dynamics ◽  
Molecular Docking ◽  
Binding Energy ◽  
Binding Site ◽  
Binding Sites ◽  
Adenosine Monophosphate ◽  
Competitive Inhibitor ◽  
Umbrella Sampling ◽  
Coarse Grained ◽  
Nucleotide Polymorphisms

Multidrug resistance protein-4 (MRP4) belongs to the ABC transporter superfamily and promotes the transport of xenobiotics including drugs. A non-synonymous single nucleotide polymorphisms (nsSNPs) in the ABCC4 gene can promote changes in the structure and function of MRP4. In this work, the interaction of certain endogen substrates, drug substrates, and inhibitors with wild type-MRP4 (WT-MRP4) and its variants G187W and Y556C were studied to determine differences in the intermolecular interactions and affinity related to SNPs using protein threading modeling, molecular docking, all-atom, coarse grained, and umbrella sampling molecular dynamics simulations (AA-MDS and CG-MDS, respectively). The results showed that the three MRP4 structures had significantly different conformations at given sites, leading to differences in the docking scores (DS) and binding sites of three different groups of molecules. Folic acid (FA) had the highest variation in DS on G187W concerning WT-MRP4. WT-MRP4, G187W, Y556C, and FA had different conformations through 25 ns AA-MD. Umbrella sampling simulations indicated that the Y556C-FA complex was the most stable one with or without ATP. In Y556C, the cyclic adenosine monophosphate (cAMP) and ceefourin-1 binding sites are located out of the entrance of the inner cavity, which suggests that both cAMP and ceefourin-1 may not be transported. The binding site for cAMP and ceefourin-1 is quite similar and the affinity (binding energy) of ceefourin-1 to WT-MRP4, G187W, and Y556C is greater than the affinity of cAMP, which may suggest that ceefourin-1 works as a competitive inhibitor. In conclusion, the nsSNPs G187W and Y556C lead to changes in protein conformation, which modifies the ligand binding site, DS, and binding energy.

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