scholarly journals The pyrophosphatase activity of pig kidney alkaline phosphatase and its inhibition by magnesium ions and excess of pyrophosphate

1968 ◽  
Vol 110 (4) ◽  
pp. 671-675 ◽  
Author(s):  
P. J. Butterworth
Keyword(s):  
Metal Ion ◽  
Total Concentration ◽  
Alkaline Phosphatases ◽  
Inorganic Pyrophosphate ◽  
Pig Kidney ◽  
A Value ◽  
Pyrophosphatase Activity ◽  
Concentration Curves ◽  
Kidney Alkaline Phosphatase ◽  
Complex Ion

1. Pig kidney enzyme resembles other non-specific alkaline phosphatases in its ability to hydrolyse inorganic pyrophosphate (PPi). 2. Studies of enzyme velocity as a function of PPi concentration show that Michaelis–Menten kinetics are obeyed when a constant PPi/Mg2+ concentration ratio is maintained, but velocity–substrate concentration curves are sigmoid when the concentration of PPi is increased but that of Mg2+ is kept constant. The enzyme is inhibited when the total PPi concentration is greater than the total concentration of Mg2+. Pyrophosphatase activity is activated by Mg2+, but if the concentration of the metal ion is increased to a value in excess of the total PPi concentration Mg2+ is then strongly inhibitory. 4. It appears that the enzyme is most active towards the complex ion MgPPi2−. The enzyme probably hydrolyses PPi4− also, but this is a poorer substrate and its competition with MgPPi2− leads to inhibition. At high Mg2+ concentrations Mg2PPi is formed. This complex appears to be a potent inhibitor. 5. Sigmoid plots of v against s and of v against i result from interactions occurring between Mg2+ and PPi4− leading to MgPPi2− and Mg2PPi, and are not indicative of allosteric behaviour.

scholarly journals Nucleoside pyrophosphatase activity associated with pig kidney alkaline phosphatase

1971 ◽  
Vol 124 (5) ◽  
pp. 891-896 ◽  
Author(s):  
Milica Wass ◽  
P. J. Butterworth
Keyword(s):  
Alkaline Phosphatase ◽  
Pig Kidney ◽  
Bivalent Cations ◽  
Free Nucleotides ◽  
Pyrophosphatase Activity ◽  
Kidney Alkaline Phosphatase

1. A study was made of the hydrolysis, at pH9.0, of ATP and ADP catalysed by pig kidney alkaline phosphatase. Both of these nucleoside pyrophosphates are substrates for the enzyme; Km values are 4×10-5m for ATP and 6.3×10-5m for ADP. Vmax. for ADP is approximately double that of ATP. 2. Above 0.1mm approximately, both ATP and ADP are inhibitory, but the inhibition is reversible by the addition of Mg2+ ions to form MgATP2- or MgADP- complexes. The complexes, besides being non-inhibitory, are also substrates for the enzyme with Km values identical with those of the respective free nucleotides. 3. Mg2+ ions are inhibitory when present in excess of ATP or ADP. The degree of inhibition is greater with ATP as substrate, but with both ATP and ADP a mixed competitive–non-competitive type of inhibition is observed. 4. It is suggested that under normal conditions the enzyme is inhibited by cellular concentrations of ATP plus ADP but that an increase in the concentration of Mg2+ ions stimulates activity by relieving nucleoside pyrophosphate inhibition. The properties may be of importance in the regulation of the transport of bivalent cations.

scholarly journals Aggregation-Induced Emission of Au/Ag Alloy Nanoclusters for Fluorescence Detection of Inorganic Pyrophosphate and Pyrophosphatase Activity

2021 ◽  
Vol 8 ◽  
Author(s):  
Zhongli Lei ◽  
Jie Zhou ◽  
Miao Liang ◽  
Yan Xiao ◽  
Zhihong Liu
Keyword(s):  
Fluorescence Detection ◽  
Metal Ion ◽  
Accurate Determination ◽  
Water Soluble ◽  
Simple Method ◽  
Inorganic Pyrophosphate ◽  
New Approach ◽  
Aggregation Induced Emission ◽  
Pyrophosphatase Activity ◽  
Ag Ncs

The development of sensitive and accurate detection of inorganic pyrophosphate (PPi) and pyrophosphatase activity (PPase) is important as they play vital roles in biological systems. However, it is still not satisfactory for most of the analytical methods for PPi and PPase because of their Cu2+-dependence and poor accuracy. Although the metal ion triggered aggregation-induced emission (AIE) of metal nanoclusters (NCs) offers a new approach to design a Cu2+-free strategy for the accurate determination of PPi and PPase recently, current methods are all focused on utilizing pure metal NCs. Alloy NCs incorporating the advantages of diverse metal usually can achieve improved behaviors in the application, such as enhanced sensitivity and stability. In this work, glutathione stabilized alloy Au/Ag NCs were synthesized via a simple method and used for the fluorescence detection of PPi and PPase based on a Zn2+-regulated AIE strategy. The controlled release of Zn2+ by PPi and PPase could regulate the AIE of Au/Ag NCs and be employed to response PPi concentration and PPase activity. This method processes simple procedure, high sensitivity and stability, and low toxicity. In addition, we also studied the AIE behaviors of this Au/Ag NCs and offer some fundamental understanding of the AIE properties of water-soluble alloy NCs. This study not only provides a straightforward and new approach for PPi and PPase determination but a basis for further study on the AIE properties of alloy NCs and their application.

The asymptotic stage of longitudinal turbulent dispersion within a tube

1977 ◽  
Vol 80 (2) ◽  
pp. 293-303 ◽  
Author(s):  
R. Dewey ◽  
Paul J. Sullivan
Keyword(s):  
Turbulent Flows ◽  
Friction Velocity ◽  
Turbulent Dispersion ◽  
Time Interval ◽  
Longitudinal Diffusion ◽  
A Value ◽  
Discharge Velocity ◽  
Concentration Curves ◽  
Temporal Growth Rate ◽  
Short Times

This paper describes an experimental investigation of the conditions for which the asymptotic description of longitudinal dispersion given by Taylor (1954) would apply. At non-dimensional times following the release of a dye pulse that are significantly larger than those previously investigated, the integrated concentration curves were observed to be skewed. At relatively short times from release the concentration curves appear to be well described by the models presented by Sullivan (1971) and by Chatwin (1973). Some features of the asymptotic behaviour, namely the translation of the modal value of the integrated concentration curve at the discharge velocity and the constant temporal growth rate of the variance, are observed at the longest times following release. On the basis of these observations it is estimated that a non-dimensional time interval oftu*/d=O(105/R*), whereR*=u*d/v,u*is the friction velocity,vthe kinematic viscosity anddthe tube diameter, is required for the Taylor result to become applicable. Thus application of Taylor's theory is significantly restricted in turbulent flows, especially those with irregular boundaries and those that are not stationary. There the variations in the flow must be small with respect to an equivalent ‘development time’ if a value of the ‘local’ longitudinal diffusion coefficient is to have meaning.

scholarly journals Evidence for the importance of arginine residues in pig kidney alkaline phosphatase

1979 ◽  
Vol 181 (1) ◽  
pp. 137-142 ◽  
Author(s):  
M N Woodroofe ◽  
P J Butterworth
Keyword(s):  
Alkaline Phosphatase ◽  
Active Site ◽  
Competitive Inhibitor ◽  
Arginine Residue ◽  
Pig Kidney ◽  
Close Proximity ◽  
Arginine Residues ◽  
Km Value ◽  
Uncompetitive Inhibitor ◽  
Kidney Alkaline Phosphatase

The arginine-specific reagents 2,3-butanedione and phenylglyoxal inactivate pig kidney alkaline phosphatase. As inactivation proceeds there is a progressive fall in Vmax. of the enzyme, but no demonstrable change in the Km value for substrate. Pi, a competitive inhibitor, and AMP, a substrate of the enzyme, protect alkaline phosphatase against the arginine-specific reagents. These effects are explicable by the assumption that the enzyme contains an essential arginine residue at the active site. Protection is also afforded by the uncompetitive inhibitor NADH through a partially competive action against the reagents. Enzyme that has been exposed to the reagents has a decreased sensitivity to NADH inhibition. It is suggested that an arginine residue is important for NADH binding also, although this residue is distinct from that at the catalytic site. The protection given by NADH against loss of activity is indicative of the close proximity of the active and NADH sites.

THE METABOLISM OF THE ERYTHROCYTE: X. THE INORGANIC PYROPHOSPHATASE OF THE ERYTHROCYTE

1956 ◽  
Vol 34 (1) ◽  
pp. 121-129 ◽  
Author(s):  
A. Malkin ◽  
O. F. Denstedt
Keyword(s):  
Enzyme Activity ◽  
Calcium Ions ◽  
Human Erythrocyte ◽  
Inorganic Pyrophosphatase ◽  
Magnesium Ions ◽  
Constant Ratio ◽  
Inorganic Pyrophosphate ◽  
Noncompetitive Inhibitor ◽  
Pyrophosphatase Activity ◽  
Hydrolysis Of

The activity of the pyrophosphatase which catalyzes the hydrolysis of inorganic pyrophosphate in the erythrocyte of the human, the rabbit, and the chicken is confined entirely to the cytoplasm of the cell. Following preincubation, the enzyme activity in the human erythrocyte is diminished, but pre-incubation in the presence of cysteine or glutathione prevents the diminution of the enzyme activity. Aging of the hemolyzate of the human erythrocytes results in a marked loss of the inorganic pyrophosphatase activity. The diminished activity can be restored by the addition of cysteine or glutathione to the reaction mixture; but after the hemolyzate has aged for five or six days at 5 °C, the loss in the enzyme activity can no longer be restored with these reagents. Fluoride and calcium ions inhibit the activity of the enzyme, while magnesium ions are essential for its activity. Calcium is a noncompetitive inhibitor, while the inhibition by fluoride is of a "quadratic" nature. If a constant ratio of magnesium to pyrophosphate is maintained, the quadratic inhibition can be converted to the "uncompetitive" type of inhibition.

Identification of Functional Groups of Pig Kidney Alkaline Phosphatase by Specific Inhibitors

1975 ◽  
Vol 30 (11-12) ◽  
pp. 829-831 ◽  
Author(s):  
Jan Ahlers
Keyword(s):  
Alkaline Phosphatase ◽  
Functional Groups ◽  
Pig Kidney ◽  
Kidney Alkaline Phosphatase ◽  
Specific Inhibitors ◽  
Regulatory Sites

Abstract Inactivation studies with 17 group-specific inhibitors showed that amino, hystidyl and tyrosyl residues probably are components of the active and/or regulatory sites of pig kidney alkaline phosphatase.

scholarly journals Organic pyrophosphates as substrates for human alkaline phosphatases

1967 ◽  
Vol 105 (3) ◽  
pp. 1307-1312 ◽  
Author(s):  
R. Helen Eaton ◽  
D W Moss
Keyword(s):  
Gel Electrophoresis ◽  
Human Liver ◽  
Inorganic Phosphate ◽  
Starch Gel Electrophoresis ◽  
Alkaline Phosphatases ◽  
Starch Gel ◽  
Pyrophosphatase Activity ◽  
Small Intestinal ◽  
Hydrolysis Of ◽  
Single Enzyme

1. Purified human liver and small-intestinal alkaline orthophosphatases release inorganic phosphate at appreciable rates from a variety of organic pyrophosphate substrates. 2. The pyrophosphatase action is inhibited by Mg2+ ions at concentrations that activate the hydrolysis of orthophosphate substrates by these enzymes. 3. The results of mixed-substrate experiments, denaturation studies with heat or urea and starch-gel electrophoresis suggest that both orthophosphatase and pyrophosphatase activities are, in each preparation, properties of a single enzyme. 4. Intestinal phosphatase shows greater pyrophosphatase activity relative to orthophosphatase than the liver enzyme.

Micelle formation as a factor influencing the mode(s) of metal ion partitioning into N-alkylpyridinium-based ionic liquids (ILs): implications for the design of IL-based extraction systems

2017 ◽  
Vol 19 (23) ◽  
pp. 5674-5682 ◽  
Author(s):  
James L. Wankowski ◽  
Michael J. Kaul ◽  
Mark L. Dietz
Keyword(s):  
Ionic Liquids ◽  
Crown Ether ◽  
Metal Ion ◽  
Alkaline Earth ◽  
Micelle Formation ◽  
Ion Pair ◽  
Neutral Complex ◽  
Ion Partitioning ◽  
Alkaline Earth Cations ◽  
Complex Ion

In the extraction of alkali and alkaline earth cations by a crown ether into certain N-alkylpyridinium-based ILs, the balance between neutral complex/ion-pair partitioning and ion exchange is significantly altered by the formation of micelles in the aqueous phase involving the IL cation.

scholarly journals Fluxionate Lewis acidity of the Zn2+ ion in carboxypeptidase A

1993 ◽  
Vol 289 (1) ◽  
pp. 185-193 ◽  
Author(s):  
W L Mock ◽  
D J Freeman ◽  
M Aksamawati
Keyword(s):  
Metal Ion ◽  
Competitive Inhibition ◽  
Dissociation Constants ◽  
Ph Dependence ◽  
Bound Water ◽  
Acid Dissociation ◽  
Lewis Acidity ◽  
Carboxypeptidase A ◽  
A Value ◽  
Straight Line

Competitive inhibition constants Ki for a series of phenol-ring-substituted derivatives of alpha-(2-hydroxyphenyl)benzenepropanoic acid have been ascertained by observing their influence on the catalytic hydrolysis of a peptide substrate by the zinc enzyme carboxypeptidase A. The pH-dependence of Ki shows that binding is maximal between two pKa values: one is that of the phenol group of the inhibitor, and the other uniformly has a value of 6, the pKa of a Zn(2+)-bound water molecule on the enzyme in the absence of substrate or inhibitor. This is the dependence expected if phenolate binds to the Zn2+ displacing its bound H2O/HO-. A log-log plot of the dissociation constants for the productive forms of inhibitor plus enzyme versus the acid dissociation constants of the phenolic residues in the inhibitors yields a straight line with a slope of +0.76. This number indicates that the active-site metal ion has special capacity for dispersing negative charge, such as builds up on the oxygen atom of a carboxamide group undergoing nucleophilic addition.

Polyamine ligands. I. The stereochemistry of transition metal complexes with the ligand 1,8-Bis(2'-pyridyl)-3,6-diazaoctane

1970 ◽  
Vol 23 (3) ◽  
pp. 491 ◽  
Author(s):  
AT Phillip ◽  
AT Casey ◽  
CR Thompson
Keyword(s):  
Transition Metal Complexes ◽  
Metal Ion ◽  
Electronic Absorption Spectra ◽  
Magnetic Moments ◽  
Temperature Dependent ◽  
Physical Measurements ◽  
Square Planar ◽  
First Time ◽  
Perchlorate Complex ◽  
Complex Ion

The new polyamine ligand 1,8-bis(2'-pyridyl)-3,6-diazaoctane has been synthesized for the first time by the reaction between 2-vinylpyridine and ethyl-enediamine. The ligand could not be distilled without decomposition and hence it was purified by converting it into the crystalline copper(11) perchlorate complex, from which the ligand was liberated by the reaction with sodium sulphide solution. The pure ligand was obtained in an overall yield of 28%, based on starting materials. The complexes formed by the ligand with the metal ions copper(11), nicke1(11), palladium(11), zinc(11), and cobalt(111) were isolated and characterized by physical measurements of their conductance in solution, magnetic moments, infrared and electronic absorption spectra. The ligand adopts the planar-N4 configuration around the metal ion in the complexes with copper(11), nicke1(11), and palladiurn(11), whereas it probably adopt's a tetrahedral-N4 configuration around the zinc(11) complex ion. The nickel(11) perchlorate complex is diamagnetic in the solid state and it most likely contains the metal ion in square-planar cordination. When dissolved in coordinating solvents, this complex undergoes a reversible, temperature-dependent equilibrium between diamagnetic and solvated, paramagnetic forms.

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