THE ROLE OF ALKALINE PHOSPHATASE IN INTESTINAL ABSORPTION I. THE KINETICS OF PHOSPHATASE ACTION ON VARIOUS SUBSTRATES

1953 ◽  
Vol 31 (1) ◽  
pp. 1-7
Author(s):  
Neil B. Madsen ◽  
Jules Tuba
Keyword(s):  
Alkaline Phosphatase ◽  
Average Energy ◽  
Inorganic Phosphorus ◽  
Intestinal Alkaline Phosphatase ◽  
Egg Lecithin ◽  
Michaelis Constants ◽  
Inhibition Studies ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of intestinal alkaline phosphatase action on sodium β-glycerophosphate, glucose 6-phosphate, and egg lecithin have been studied and compared. The Michaelis constants indicate that the enzyme shows considerably less affinity for lecithin than for the other two substrates, and the approximate ratio of activity with lecithin, glucose 6-phosphate, and sodium β-glycerophosphate is 11 : 78.5 : 100. The energies of activation for the hydrolysis of the three substrates do not differ appreciably and the average energy of activation is 14,500 calories per gram-mole. The similarity of the energies of activation together with results from inhibition studies indicate that in all probability the same enzyme is responsible for the release of inorganic phosphorus from each of the three substrates.

scholarly journals Chicken Intestinal Alkaline Phosphatase

1960 ◽  
Vol 43 (6) ◽  
pp. 1149-1169 ◽  
Author(s):  
M. Kunitz
Keyword(s):  
Alkaline Phosphatase ◽  
Zinc Ions ◽  
Magnesium Ions ◽  
Intestinal Alkaline Phosphatase ◽  
Reversible Inactivation ◽  
Higher Temperature ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Zn Ions ◽  
Denaturation Of Proteins

Purified chicken intestinal alkaline phosphatase is active at pH 8 to 9, but becomes rapidly inactivated with change of pH to 6 or less. Also, a solution of the inactivated enzyme at pH 4.5 rapidly regains its activity at pH 8. In the range of pH 6 to 8 a solution of purified alkaline phosphatase consists of a mixture of active and inactive enzyme in equilibrium with each other. The rate of inactivation at lower pH and of reactivation at higher pH increases with increase in temperature. Also, the activity at equilibrium in the range of pH 6 to 8 increases with temperature so that a solution equilibrated at higher temperature loses part of its activity on cooling, and vice versa, a rise in temperature shifts the equilibrium toward higher activity. The kinetics of inactivation of the enzyme at lower pH and the reactivation at higher pH is that of a unimolecular reaction. The thermodynamic values for the heat and entropy of the reversible inactivation and reactivation of the enzyme are considerably lower than those observed for the reversible denaturation of proteins. The inactivated enzyme at pH 4 to 6 is rapidly reactivated on addition of Zn ions even at pH 4 to 6. However, zinc ions are unable to replace magnesium ions as cocatalysts for the enzymatic hydrolysis of organic phosphates by alkaline phosphatase.

Influence of pH on the Kinetics of Reactions Catalyzed by Alkaline Phosphatase

1973 ◽  
Vol 51 (7) ◽  
pp. 1096-1103 ◽  
Author(s):  
Irwin Hinberg ◽  
Keith J. Laidler
Keyword(s):  
Alkaline Phosphatase ◽  
Intestinal Alkaline Phosphatase ◽  
Nitrophenyl Phosphate ◽  
Wide Range ◽  
Coordinated Water ◽  
Ph Range ◽  
Barbital Buffer ◽  
Influence Of Ph ◽  
Kinetics Of ◽  
Hydrolysis Of

An experimental study has been made of the kinetics of the hydrolysis of p-nitrophenyl phosphate catalyzed by chicken-intestinal alkaline phosphatase. The work was done in barbital buffer (carbonate above pH 9.6), and covered the pH range from 7.0 to 10.0. A sufficiently wide range of substrate concentration was used to allow reliable values of [Formula: see text] and [Formula: see text] to be determined. The results lead to pK values of 8.1 and 8.6 for the free enzyme, and it is concluded that the Michaelis complex and the phosphoryl intermediate ionize only on the acid side, the former also having a pK of 8.1. It is suggested that the group of pK 8.1 is probably an α-amino group and that the group of pK 8.6 probably corresponds to the ionization of a Zn(II)-coordinated water molecule.

THE ROLE OF ALKALINE PHOSPHATASE IN INTESTINAL ABSORPTION: IV. THE EFFECTS OF VARIOUS PROTEINS ON LEVELS OF THE ENZYME IN INTESTINAL MUCOSA

1955 ◽  
Vol 33 (1) ◽  
pp. 89-92 ◽  
Author(s):  
Jules Tuba ◽  
Nester Dickie
Keyword(s):  
Alkaline Phosphatase ◽  
Intestinal Absorption ◽  
Intestinal Mucosa ◽  
Adult Male ◽  
Wheat Gluten ◽  
Male Rats ◽  
Dietary Proteins ◽  
Intestinal Alkaline Phosphatase ◽  
Egg Albumin

Fasted adult male rats were used to study the effect of dietary proteins on intestinal alkaline phosphatase. Groups of animals were offered one of several proteins; lactalbumin, egg albumin, zein, gelatin, wheat gluten, casein, and vitellin. Control animals had cellulose fed to them. The rats were sacrificed six hours after they were given the different diets. Alkaline phosphatase determinations with intestinal homogenates indicated that the two phosphoproteins, casein and vitellin, elevated levels of the enzyme significantly above fasting levels. Possible interpretations of these findings are discussed.

The Protective Role of Intestinal Alkaline Phosphatase in Necrotizing Enterocolitis

2010 ◽  
Vol 158 (2) ◽  
pp. 201
Author(s):  
J.S. Whitehouse ◽  
K.M. Riggle ◽  
D.P. Purpi ◽  
A.N. Mayer ◽  
K.A. Pritchard ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Necrotizing Enterocolitis ◽  
Protective Role ◽  
Intestinal Alkaline Phosphatase

W1548 Role of Lysophosphatidylcholine in Intestinal Alkaline Phosphatase Release and Restoration

2009 ◽  
Vol 136 (5) ◽  
pp. A-689
Author(s):  
Takanari Nakano ◽  
Ikuo Inoue ◽  
David H. Alpers ◽  
Rina Shinozaki ◽  
Jonathan D. Kaunitz ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Intestinal Alkaline Phosphatase

scholarly journals Inhibition of the orthophosphatase and pyrophosphatase activities of human alkaline-phosphatase preparations

1967 ◽  
Vol 102 (3) ◽  
pp. 917-921 ◽  
Author(s):  
R.H. Eaton ◽  
D. W. Moss
Keyword(s):  
Alkaline Phosphatase ◽  
Competitive Inhibitor ◽  
Tissue Preparation ◽  
Intestinal Alkaline Phosphatase ◽  
Active Centre ◽  
Low Concentrations ◽  
Type 3 ◽  
Intestinal Preparation ◽  
Hydrolysis Of ◽  
Single Enzyme

1. Inhibition of the pyrophosphatase and orthophosphatase activities of human liver and small-intestinal alkaline-phosphatase preparations by different classes of inhibitors has been studied. 2. Each type of substrate, pyrophosphate or orthophosphate, is a competitive inhibitor of hydrolysis of the other type. 3. l-Phenylalanine is a non-competitive inhibitor of both types of activity of the intestinal preparation, but inhibits neither activity of the liver enzyme. Arsenate is a competitive inhibitor of both activities of both preparations. For a given inhibitor, the values of K(i) are independent of the type of substrate used when measurements are made at the same pH. 4. Mg(2+) ions activate orthophosphatase but inhibit pyrophosphatase, except in very low concentrations. 5. These results are compatible with the presence in each tissue preparation of a single enzyme with one type of active centre, possessing both orthophosphatase and pyrophosphatase activities.

Role of intestinal alkaline phosphatase in calcium absorption

Bone ◽  
2016 ◽  
Vol 89 ◽  
pp. 68
Author(s):  
L.R. Brun ◽  
D. Lescano ◽  
S. Roma ◽  
J.L. Millán ◽  
A. Rigalli
Keyword(s):  
Alkaline Phosphatase ◽  
Calcium Absorption ◽  
Intestinal Alkaline Phosphatase

scholarly journals Characterization of human foetal intestinal alkaline phosphatase. Comparison with the isoenzymes from the adult intestine and human tumour cell lines

1983 ◽  
Vol 211 (3) ◽  
pp. 553-558 ◽  
Author(s):  
C M Behrens ◽  
C A Enns ◽  
H H Sussman
Keyword(s):  
Alkaline Phosphatase ◽  
Cell Line ◽  
Tumour Cell ◽  
Tumour Cell Line ◽  
Subunit Structure ◽  
Human Tumour ◽  
Intestinal Alkaline Phosphatase ◽  
Alkaline Phosphatases ◽  
Inhibition Studies

The molecular structure of human foetal intestinal alkaline phosphatase was defined by high-resolution two-dimensional polyacrylamide-gel electrophoresis and amino acid inhibition studies. Comparison was made with the adult form of intestinal alkaline phosphatase, as well as with alkaline phosphatases isolated from cultured foetal amnion cells (FL) and a human tumour cell line (KB). Two non-identical subunits were isolated from the foetal intestinal isoenzyme, one having same molecular weight and isoelectric point as placental alkaline phosphatase, and the other corresponding to a glycosylated subunit of the adult intestinal enzyme. The FL-cell and KB-cell alkaline phosphatases were also found to contain two subunits similar to those of the foetal intestinal isoenzyme. Characterization of neuraminidase digests of the non-placental subunit showed it to be indistinguishable from the subunits of the adult intestinal isoenzyme. This implies that no new phosphatase structural gene is involved in the transition from the expression of foetal to adult intestinal alkaline phosphatase, but that the molecular changes involve suppression of the placental subunit and loss of neuraminic acid from the non-placental subunit. Enzyme-inhibition studies demonstrated an intermediate response to the inhibitors tested for the foetal intestinal, FL-cell and KB-cell isoenzymes when compared with the placental, adult intestinal and liver forms. This result is consistent with the mixed-subunit structure observed for the former set of isoenzymes. In summary, this study has defined the molecular subunit structure of the foetal intestinal form of alkaline phosphatase and has demonstrated its expression in a human tumour cell line.

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