Role of Metal Ion in Specific Recognition of Pyrophosphate Ion under Physiological Conditions and Hydrolysis of the Phosphoester Linkage by Alkaline Phosphatase

2013 ◽  
Vol 52 (19) ◽  
pp. 11034-11041 ◽  
Author(s):  
Priyadip Das ◽  
Nellore Bhanu Chandar ◽  
Shishir Chourey ◽  
Hridesh Agarwalla ◽  
Bishwajit Ganguly ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Metal Ion ◽  
Physiological Conditions ◽  
Specific Recognition ◽  
Hydrolysis Of

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 Evolutionary Expansion of the Amidohydrolase Superfamily in Bacteria in Response to the Synthetic Compounds Molinate and Diuron

2015 ◽  
Vol 81 (7) ◽  
pp. 2612-2624 ◽  
Author(s):  
Elena Sugrue ◽  
Nicholas J. Fraser ◽  
Davis H. Hopkins ◽  
Paul D. Carr ◽  
Jeevan L. Khurana ◽  
...  
Keyword(s):  
Active Site ◽  
Metal Ion ◽  
Active Sites ◽  
Evolutionary Transition ◽  
Functional Changes ◽  
Metal Ion Analysis ◽  
Amidohydrolase Superfamily ◽  
Kinetics Of ◽  
Hydrolysis Of

ABSTRACTThe amidohydrolase superfamily has remarkable functional diversity, with considerable structural and functional annotation of known sequences. In microbes, the recent evolution of several members of this family to catalyze the breakdown of environmental xenobiotics is not well understood. An evolutionary transition from binuclear to mononuclear metal ion coordination at the active sites of these enzymes could produce large functional changes such as those observed in nature, but there are few clear examples available to support this hypothesis. To investigate the role of binuclear-mononuclear active-site transitions in the evolution of new function in this superfamily, we have characterized two recently evolved enzymes that catalyze the hydrolysis of the synthetic herbicides molinate (MolA) and phenylurea (PuhB). In this work, the crystal structures, mutagenesis, metal ion analysis, and enzyme kinetics of both MolA and PuhB establish that these enzymes utilize a mononuclear active site. However, bioinformatics and structural comparisons reveal that the closest putative ancestor of these enzymes had a binuclear active site, indicating that a binuclear-mononuclear transition has occurred. These proteins may represent examples of evolution modifying the characteristics of existing catalysts to satisfy new requirements, specifically, metal ion rearrangement leading to large leaps in activity that would not otherwise be possible.

scholarly journals Selective inhibition of Zn2+-glycerophosphocholine cholinephosphodiesterase by tellurium tetrachloride

1992 ◽  
Vol 284 (3) ◽  
pp. 641-643 ◽  
Author(s):  
D E Sok ◽  
M R Kim
Keyword(s):  
Metal Ions ◽  
Mouse Brain ◽  
Selective Inhibition ◽  
Inhibitory Effect ◽  
Physiological Conditions ◽  
Neutral Ph ◽  
Tellurium Tetrachloride ◽  
Hydrolysis Of ◽  
Competitive Pattern

A Zn(2+)-glycerophosphocholine cholinephosphodiesterase (EC 3.1.4.38) purified from mouse brain was found to be reversibly inhibited by tellurium tetrachloride. This effect was characterized by a competitive pattern of inhibition, with apparent Ki values of 0.7 microM and 1.5 microM for the hydrolysis of p-nitrophenylphosphocholine and glycerophosphocholine respectively. Interestingly, the inhibitory effect of tellurium tetrachloride was found to be greatly potentiated by tetramethylammonium salt, indicative of a synergistic interaction between the two compounds. Additionally, it was observed that the effect of tellurium tetrachloride was not affected by a number of other metal ions, and was more pronounced at neutral pH, suggesting that the inhibitory role of the tellurium tetrachloride may be of importance under physiological conditions. Thus Zn(2+)-glycerophosphocholine cholinephosphodiesterase is proposed to be one of the target enzymes which is susceptible to the inhibitory effect of tellurium tetrachloride.

scholarly journals Extracellular pyrophosphate metabolism and calcification in vascular smooth muscle

2011 ◽  
Vol 301 (1) ◽  
pp. H61-H68 ◽  
Author(s):  
Ricardo Villa-Bellosta ◽  
Xiaonan Wang ◽  
José Luis Millán ◽  
George R. Dubyak ◽  
W. Charles O'Neill
Keyword(s):  
Alkaline Phosphatase ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Vascular Calcification ◽  
Endogenous Inhibitor ◽  
Inorganic Pyrophosphate ◽  
Inhibitory Role ◽  
Tissue Nonspecific Alkaline Phosphatase ◽  
Hydrolysis Of

Extracellular inorganic pyrophosphate (ePPi) is an important endogenous inhibitor of vascular calcification, but it is not known whether systemic or local vascular PPi metabolism controls calcification. To determine the role of ePPi in vascular smooth muscle, we identified the pathways responsible for ePPi production and hydrolysis in rat and mouse aortas and manipulated them to demonstrate their role in the calcification of isolated aortas in culture. Rat and mouse aortas contained mRNA for ectonucleotide pyrophosphatase/phosphodiesterases (NPP1–3), the putative PPi transporter ANK, and tissue-nonspecific alkaline phosphatase (TNAP). Synthesis of PPi from ATP in aortas was blocked by β,γ-methylene-ATP, an inhibitor of NPPs. Aortas from mice lacking NPP1 ( Enpp1−/−) did not synthesize PPi from ATP and exhibited increased calcification in culture. Although ANK-mediated transport of PPi could not be demonstrated in aortas, aortas from mutant ( ank/ank) mice calcified more in culture than did aortas from normal (ANK/ANK) mice. Hydrolysis of PPi was reduced 25% by β,γ-methylene-ATP and 50% by inhibition of TNAP. Hydrolysis of PPi was increased in cells overexpressing TNAP or NPP3 but not NPP1 and was not reduced in Enpp1−/− aortas. Overexpression of TNAP increased calcification of cultured aortas. The results show that smooth muscle NPP1 and TNAP control vascular calcification through effects on synthesis and hydrolysis of ePPi, indicating an important inhibitory role of locally produced PPi. Smooth muscle ANK also affects calcification, but this may not be mediated through transport of PPi. NPP3 is identified as an additional pyrophosphatase that could influence vascular calcification.

Hydrolysis of Dinitrobenzamide Phosphate Prodrugs: The Role of Alkaline Phosphatase

2009 ◽  
Vol 24 (1) ◽  
pp. 1-16 ◽  
Author(s):  
W.-Y. Lo ◽  
A. Balasubramanian ◽  
N.A. Helsby ◽  
New Zealand
Keyword(s):  
Alkaline Phosphatase ◽  
Hydrolysis Of

scholarly journals The activity of the dinuclear cobalt-β-lactamase from Bacillus cereus in catalysing the hydrolysis of β-lactams

2006 ◽  
Vol 401 (1) ◽  
pp. 197-203 ◽  
Author(s):  
Adriana Badarau ◽  
Christian Damblon ◽  
Michael I. Page
Keyword(s):  
Catalytic Activity ◽  
Bacillus Cereus ◽  
Metal Ion ◽  
Active Form ◽  
Metal Ion Binding ◽  
Deprotonated Form ◽  
Efficient Catalyst ◽  
Zinc Enzymes ◽  
Hydrolysis Of

Metallo-β-lactamases are native zinc enzymes that catalyse the hydrolysis of β-lactam antibiotics, but are also able to function with cobalt(II) and require one or two metal-ions for catalytic activity. The hydrolysis of cefoxitin, cephaloridine and benzylpenicillin catalysed by CoBcII (cobalt-substituted β-lactamase from Bacillus cereus) has been studied at different pHs and metal-ion concentrations. An enzyme group of pKa 6.52±0.1 is found to be required in its deprotonated form for metal-ion binding and catalysis. The species that results from the loss of one cobalt ion from the enzyme has no significant catalytic activity and is thought to be the mononuclear CoBcII. It appears that dinuclear CoBcII is the active form of the enzyme necessary for turnover, while the mononuclear CoBcII is only involved in substrate binding. The cobalt-substituted enzyme is a more efficient catalyst than the native enzyme for the hydrolysis of some β-lactam antibiotics suggesting that the role of the metal-ion is predominantly to provide the nucleophilic hydroxide, rather than to act as a Lewis acid to polarize the carbonyl group and stabilize the oxyanion tetrahedral intermediate.

Extracellular enzymatic activities in the aquatic ecosystems of the Danube Delta. 2. Alkaline phosphatase activity

2021 ◽  
Vol 26 (1) ◽  
pp. 2269-2274
Author(s):  
IOAN PĂCEŞILĂ ◽  
EMILIA RADU
Keyword(s):  
Alkaline Phosphatase ◽  
Water Column ◽  
Aquatic Ecosystems ◽  
Temporal Dynamics ◽  
Extracellular Enzyme ◽  
Danube Delta ◽  
Phytoplankton Communities ◽  
Extracellular Enzymatic Activities ◽  
Adjacent Channels ◽  
Hydrolysis Of

Phosphorus is one of the most important inorganic nutrients in aquatic ecosystems, the development and functioning of the phytoplankton communities being often correlated with the degree of availability in assimilable forms of this element. Alkaline phosphatase (AP) is an extracellular enzyme with nonspecific activity that catalyses the hydrolysis of a large variety of organic phosphate esters and release orthophosphates. During 2011-2013, AP Activity (APA) was assessed in the water column and sediments of several aquatic ecosystems from Danube Delta: Roșu Lake, Mândra Lake and their adjacent channels – Roșu-Împuțita and Roșu-Puiu. The intensity of APA widely fluctuated, ranging between 230-2578 nmol p-nitrophenol L-1h-1 in the water column and 2104-15631 nmol p-nitrophenol g-1h-1 in sediment. Along the entire period of the study, APA was the most intense in Roșu-Împuțita channel, for both water and sediment samples. Temporal dynamics revealed its highest values in summer for the water column and in autumn for sediment. Statistical analysis showed significant seasonal diferences of the APA dynamics in spring vs. summer and autumn for the water column, and any relevant diferences for sediment.

Involvement of Heme Oxygenase-1 in Neuropsychiatric and Neurodegenerative Diseases

2018 ◽  
Vol 24 (20) ◽  
pp. 2283-2302 ◽  
Author(s):  
Vivian B. Neis ◽  
Priscila B. Rosa ◽  
Morgana Moretti ◽  
Ana Lucia S. Rodrigues
Keyword(s):  
Neurodegenerative Diseases ◽  
Heme Oxygenase ◽  
Therapeutic Potential ◽  
Redox Homeostasis ◽  
Antioxidant Defenses ◽  
Heme Oxygenase 1 ◽  
Physiological Conditions ◽  
And Oxidative Stress ◽  
Defensive Mechanism

Heme oxygenase (HO) family catalyzes the conversion of heme into free iron, carbon monoxide and biliverdin. It possesses two well-characterized isoforms: HO-1 and HO-2. Under brain physiological conditions, the expression of HO-2 is constitutive, abundant and ubiquitous, whereas HO-1 mRNA and protein are restricted to small populations of neurons and neuroglia. HO-1 is an inducible enzyme that has been shown to participate as an essential defensive mechanism for neurons exposed to oxidant challenges, being related to antioxidant defenses in certain neuropathological conditions. Considering that neurodegenerative diseases (Alzheimer’s Disease (AD), Parkinson’s Disease (PD) and Multiple Sclerosis (MS)) and neuropsychiatric disorders (depression, anxiety, Bipolar Disorder (BD) and schizophrenia) are associated with increased inflammatory markers, impaired redox homeostasis and oxidative stress, conditions that may be associated with alterations in HO-levels/activity, the purpose of this review is to present evidence on the possible role of HO-1 in these Central Nervous System (CNS) diseases. In addition, the possible therapeutic potential of targeting brain HO-1 is explored in this review.

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