Topic
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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TL;DR: Since the product formed with poly(A) lacks 3'-hydroxyl ends, as measured with these exonucleases, the enzyme appears to convert linear molecules of polyriboadenylate to a circular form by the intramolecular covalent linkage of the 5'-phosphate end to the 3'-Hydroxyl terminus.
Abstract: An enzyme, purified 300-fold from Escherichia coli infected with bacteriophage T4, catalyzes the conversion of 5′-termini of polyribonucleotides to internal phosphodiester bonds. The reaction requires ATP and Mg++. For every 5′-32P terminus rendered resistant to alkaline phosphatase, an equal amount of AMP and PPi are formed. Various polyribonucleotides are substrates in the reaction; to date, the best substrate is [5′-32P]polyriboadenylate. With the latter substrate, no evidence of intermolecular reaction was obtained. However, the 5′-32P termini of poly(A) rendered resistant to alkaline phosphatase are also resistant to attack by RNase II, polynucleotide phosphorylase, and low concentrations of venom phosphodiesterase. Since the product formed with poly(A) lacks 3′-hydroxyl ends, as measured with these exonucleases, the enzyme appears to convert linear molecules of polyriboadenylate to a circular form by the intramolecular covalent linkage of the 5′-phosphate end to the 3′-hydroxyl terminus.
197 citations
TL;DR: Findings give further support for the view that an important factor in the development of the hypocalcaemia and occasional clinical osteomalacia in epileptics on anticonvulsant drugs is an alteration of vitamin-D metabolism in the liver as a result of microsomal enzyme induction.
Abstract: A survey of 105 epileptic children aged 10-16 years at a residential school who were taking anticonvulsant drugs showed reduced serum calcium levels in 30% and a raised serum alkaline phosphatase in 24%. Urinary D-glucaric acid excretion, a quantitative index of hepatic enzyme induction, was raised in 94% of the children, and statistical analysis showed a significant inverse correlation with the level of serum calcium. These findings give further support for the view that an important factor in the development of the hypocalcaemia and occasional clinical osteomalacia in epileptics on anticonvulsant drugs is an alteration of vitamin-D metabolism in the liver as a result of microsomal enzyme induction. As a consequence there is an increased requirement for vitamin D which may not be met by average intakes in Britain.
197 citations
TL;DR: Although the rat K- NPPase appeared almost completely insensitive to ouabain with this cytochemical medium, parallel studies with the more glycoside-sensitive rabbit kidney indicated that K-NPPase activity in these nephron segments is sensitive to this inhibitor.
Abstract: A cytochemical method for the light and electron microscope localization of the K- and Mg-dependent phosphatase component of the Na-K-ATPase complex was applied to rat kidney cortex, utilizing p-nitrophenylphosphate (NPP) as substrate. Localization of K-N-ATPase activity in kidneys fixed by perfusion with 1% paraformaldehyde -0.25% glutaraldehyde demonstrated that distal tubules are the major cortical site for this sodium transport enzyme. Cortical collecting tubules were moderately reactive, whereas activity in proximal tubules was resolved only after short fixation times and long incubations. In all cases, K-NPPase activity was restricted to the cytoplasmic side of the basolateral plasma membranes, which are characterized in these neplron segments by elaborate folding of the cell surface. Although the rat K-NPPase appeared almost completely insensitive to ouabain with this cytochemical medium, parallel studies with the more glycoside-sensitive rabbit kidney indicated that K-NPPase activity in these nephron segments is sensitive to this inhibitor. In addition to K-NPPase, nonspecific alkaline phosphatase also hydrolyzed NPP. The latter could be differentiated cytochemically from the specific phosphatase, since alkaline phosphatase was K-independent, insensitive to ouabain, and specifically inhibited by cysteine. Unlike K-NPPPase, alkaline phosphatase was localized primarily to the extracellular side of the microvillar border of proximal tubules. A small amount of cysteine-sensitive activity was resolved along peritubular surfaces of proximal tubules. Distal tubules were unreactive. In comparative studies, Mg-ATPase activity was localized along the extracellular side of the luminal and basolateral surfaces of proximal and distal tubules and the basolateral membranes of collecting tubules.
197 citations
TL;DR: The results suggest that flavonols derivatives as quercetin and kaempferol can stimulate osteoblastic activity, and such compounds may represent new pharmacological tools for the treatment of osteoporosis.
196 citations
TL;DR: It is demonstrated that the surface roughness itself caused increases in osteoblastic proliferation and differentiation in cell cultures by excluding factors other than roughness.
196 citations