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Alkaline phosphatase

About: Alkaline phosphatase is a research topic. Over the lifetime, 20218 publications have been published within this topic receiving 540547 citations. The topic is also known as: Alkaline_phosphatase & IPR001952.


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Journal ArticleDOI
TL;DR: It is certain that alkaline phosphatase is indispensable in normal ossification; it is generally instrumental in abnormal calcifications, but in a few cases calcification occurs without it.
Abstract: Summary Researches of the past ten years bearing on the physiological significance of the common acid and alkaline phosphomonoesterases may be summarized in the following facts and concepts, (i) The alkaline phos-phomonoesterase appears to be a salt-soluble, the acid a water-soluble, substance; both consist of a metallic coenzyme and a protein-like carrier. Neither depends oh sulphydryl groups for activity, but the alkaline phosphatase seems to require amine and phenolic hydroxy! groups; it is affected only by strong oxidizing agents. There is not yet any incontestable evidence that alkaline phosphomonoesterases of different sources are not identical. (2) Phosphatases probably catalyse only hydrolyses, not syntheses. (3) The content of both phosphatases in the blood serum is characteristic of age and physiological state, and is used in the diagnosis of bone and liver disorders; biliary obstruction results in elevation of serum alkaline phosphatase probably because phosphatase is normally excreted by way of liver and gut, but other explanations are possible. Diet influences serum alkaline phosphatase level. (4) The study of phosphatase function has been advanced by the development of techniques for the histochemical demonstration of acid and alkaline phosphatases. (5) It is certain that alkaline phosphatase is indispensable in normal ossification; it is generally instrumental in abnormal calcifications, but in a few cases calcification occurs without it. (6) Glycolysis seems to accompany normal bone formation, but this fact does not clarify all the unsolved problems of ossification. (7) Hormones and vitamins influence both alkaline phosphatase activity and bone formation. (8) In kidney tubules alkaline phosphatase probably functions in dephosphorylating sugar molecules that are removed from the tubular fluid by phosphorylation. The enzyme is present at other sites where it might serve in a similar manner. (9) Phosphatases are commonly found in the cytoplasm of growing, regenerating, and secreting cells in which protein synthesis is being carried on; there appears to be a correlation in such cells between content of pentosenucleic acid and of phosphatase. In dividing nuclei, phosphatase parallels desoxyribonucleic acid. (10) Acid phosphatase is found in seminal fluid, and may help to nourish the sperm. (11) The occurrence of two common phosphomonoesterases with widely different pH optima may indicate a mechanism for allowing two dephosphorylating steps to go on simultaneously in a single cell. In tissues which carry on much traffic in glycogen, acid phosphatase is possibly provided to prevent bone formation. (12) The actual role which the phosphatases play in the physiology of the organism will be understood only with elucidation of the complete enzyme systems of which the phosphatases are a part.

185 citations

Journal ArticleDOI
TL;DR: Histological examination revealed an accelerated transport of fat droplets through the intestinal epithelium and elevation of serum triglyceride levels in the IAP-deficient mice compared to wild-type mice, suggesting that IAP participates in a rate-limiting step regulating fat absorption.
Abstract: Intestinal alkaline phosphatase (IAP) is the most ancestral of the tissue-specific members of the AP gene family. Several studies have suggested an absorptive function for IAP, but in vivo data to this effect have been lacking. We inactivated the mouse IAP gene in embryo-derived stem cells and generated mice homozygous for the null mutation. The mice were macroscopically and histologically normal and fertile and showed no difference from the wild-type controls under normal laboratory conditions. However, when maintained long-term on a high-fat diet, the IAP-deficient mice showed faster body weight gain than did control animals. Histological examination revealed an accelerated transport of fat droplets through the intestinal epithelium and elevation of serum triglyceride levels in the IAP-deficient mice compared to wild-type mice. Our study suggests that IAP participates in a rate-limiting step regulating fat absorption.

184 citations

Journal ArticleDOI
TL;DR: A method is described in which enzyme amplification is used for the quantitative determination of placental alkaline phosphatase through dephosphorylation of NADP to NAD which activates a strictly NAD-dependent redox cycle leading to the formation of a coloured product.

183 citations

Journal ArticleDOI
TL;DR: Differences in substrate-activity relationships, and inhibition by l -phenylalanine and NaF provided additional support for the hydrolysis of phytate as an activity distinct from that promoting hydroleysis of p -nitrophenyl or 3-glycerophosphates.

183 citations

01 Jan 2006
TL;DR: This mini-review focuses exclusively on structural and functional features of mammalian alkaline phosphatases as identified by crystallography and probed by site-directed mutagenesis and kinetic analysis.
Abstract: Our knowledge of the structure and function of alkaline phosphatases has increased greatly in recent years. The crystal structure of the human placental isozyme has enabled us to probe salient features of the mammalian enzymes that differ from those of the bacterial enzymes. The availability of knockout mice deficient in each of the murine alkaline phosphatase isozymes has also given deep insights into their in vivo role. This has been particularly true for probing the biological role of bone alkaline phosphatase during skeletal mineralization. Due to space constraints this mini-review focuses exclusively on structural and functional features of mammalian alkaline phosphatases as identified by crystallography and probed by site-directed mutagenesis and kinetic analysis. An emphasis is also placed on the substrate specificity of alkaline phosphatases, their catalytic properties as phosphohydrolases as well as phosphodiesterases and their structural and functional relatedness to a large superfamily of enzymes that includes nucleotide pyrophosphatase/phosphodiesterase. Abbreviations: ADP – adenosine diphosphate; AMP – adenosine monophosphate; AP – alkaline phosphatase; ATP – adenosine triphosphate; cAMP – cyclic AMP; ECAP – Escherichia coli AP; GCAP – germ cell alkaline phosphatase; GPI – glycosylphosphatidylinositol; IAP – intestinal alkaline phosphatase; iPGM – cofactor-independent phosphoglycerate mutase; kcat – catalytic rate constant; Ki – inhibition constant; Km – Michaelis constant; NPP1 – nucleosidetriphosphate pyrophosphohydrolase-1; Pi – inorganic phosphate; PLAP – placental alkaline phosphatase; PLP – pyridoxal-5-phosphate; pNPP – p-nitrophenylphosphate; PPi – inorganic pyrophosphate; TNAP – tissue-nonspecific alkaline phosphatase; Vmax – maximal velocity; Wt – wild-type

183 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
2023795
20221,761
2021271
2020302
2019294