Catalytic cofactors (Mg2+ and Zn2+ ions) influence the pattern of vanadate Inhibition of the monoesterase activity of calf intestinal alkaline phosphatase

The mechanism of modulation of vanadate inhibition of alkaline phosphatase activity by catalytic cofactors has not been fully characterized. We investigated the effect of the interaction of catalytic cofactors (Mg2+ and Zn2+) and vanadate (an active site inhibitor) on the rate of hydrolysis of para-nitrophenyl phosphate (pNPP) (monoesterase reaction) by calf intestinal alkaline phosphatase (CIAP). The results showed that vanadate significantly inhibited ʻcofactor-freeʼ CIAP, and the inhibition was relieved by the presence of the catalytic cofactors in the reaction. Our results show that the absence of the cofactors did not significantly alter the Km of the reaction, but caused a decrease in the Vmax. Kinetic analyses showed that vanadate inhibited CIAP-catalyzed hydrolysis of pNPP by decreasing the Vmax and increasing the Km of the reaction. The presence of cofactors in the reaction alleviated the effect of vanadate by increasing the Vmax and decreasing the Km. The activity of the dialyzed CIAP was increased by the addition of catalytic cofactors to vanadate-inhibited enzyme. This study provides preliminary data that reversible inhibition of CIAP is subject to the influence of catalytic cofactors. Further studies will reveal detailed mechanistic aspects of this observation and its significance in the biological system.Keywords: alkaline phosphatase, monoesterase reaction, vanadate inhibition, catalytic cofactor

Treatment of produced water by simultaneous removal of heavy metals and dissolved polycyclic aromatic hydrocarbons in a photoelectrochemical cell

Early produced water treatment technologies were developed before carbon dioxide emissions and hazardous waste discharge were recognised as operational priority. These technologies are deficient in the removal of dissolved hydrocarbons and dissolved heavy metal ions which have been identified as major contributors to the high environmental impact factor of produced water. The simultaneous removal of heavy metals and polycyclic aromatic hydrocarbon (PAH) from produced water via photoelectrochemical process was identified in this work as a produced water treatment alternative with the potential to virtually eliminate the cost for chemical reagents and high energy input. Several grades of simulated produced water were synthesised and used to understand different parameters necessary for developing a successful photoelectrochemical treatment. The process demonstrated in this work followed a simple two–electrode photoelectrochemical cell where heavy metals were recovered on a platinum electrode with simultaneous degradation of PAH (phenanthrene) on a photoanode, with the aid of sunlight (simulated) and an applied cell voltage of 1.0 V. Multiwall CNT-TiO2 synthesised via a modified sol-gel method served as the photoanode after it was immobilised at a loading of 2.5 mg/cm2 on a titanium plate. The results obtained from the photoelectrochemical treatment showed a recovery of 1.6 g/cm2 of lead, 0.2 g/cm2 of copper and 0.1 g/cm2 of nickel from produced water on a 0.1 cm diameter platinum electrode after 24 hours of irradiation with simulated sunlight at 1.0 V cell voltage and a simultaneous degradation of up to 16 % phenanthrene on the photoanode, which gives a potential of scaling up the process to a commercial throughput

Cofactor interactions in the activation of tissue non-specific alkaline phosphatase: Synergistic effects of Zn2+ and Mg2+ ions

The interactions of Mg2+ and Zn2+ ions in the activation of non-specific tissue alkaline phosphatase were investigated using crude extracts of rat kidney. Activation of alkaline phosphatase by the metal ions was accompanied by changes in the kinetic parameters of  nitrophenylphosphate hydrolysis. The results suggest some synergistic interactions between Mg2+ and Zn2+ ions in promoting the hydrolysis of p-nitrophenylphosphate by alkaline phosphatase. The results show that assays of alkaline phosphatase activity in homogenised tissuesamples will give better responses if both Mg2+ and Zn2+ ions are included in the reaction

Treatment of produced water by simultaneous removal of heavy metals and dissolved polycyclic aromatic hydrocarbons in a photoelectrochemical cell

Early produced water treatment technologies were developed before carbon dioxide emissions and hazardous waste discharge were recognised as operational priority. These technologies are deficient in the removal of dissolved hydrocarbons and dissolved heavy metal ions which have been identified as major contributors to the high environmental impact factor of produced water. The simultaneous removal of heavy metals and polycyclic aromatic hydrocarbon (PAH) from produced water via photoelectrochemical process was identified in this work as a produced water treatment alternative with the potential to virtually eliminate the cost for chemical reagents and high energy input. Several grades of simulated produced water were synthesised and used to understand different parameters necessary for developing a successful photoelectrochemical treatment. The process demonstrated in this work followed a simple two–electrode photoelectrochemical cell where heavy metals were recovered on a platinum electrode with simultaneous degradation of PAH (phenanthrene) on a photoanode, with the aid of sunlight (simulated) and an applied cell voltage of 1.0 V. Multiwall CNT-TiO2 synthesised via a modified sol-gel method served as the photoanode after it was immobilised at a loading of 2.5 mg/cm2 on a titanium plate. The results obtained from the photoelectrochemical treatment showed a recovery of 1.6 g/cm2 of lead, 0.2 g/cm2 of copper and 0.1 g/cm2 of nickel from produced water on a 0.1 cm diameter platinum electrode after 24 hours of irradiation with simulated sunlight at 1.0 V cell voltage and a simultaneous degradation of up to 16 % phenanthrene on the photoanode, which gives a potential of scaling up the process to a commercial throughput

Activation of Rat Intestinal Alkaline Phosphatase by Taurine May be an Alternative Mechanism of Endotoxemic Injury Protection

Investigation of the effect of taurine on the hydrolysis of para-nitrophenylphosphate (p-NPP) by rat intestinal alkaline phosphatase (ALP), L-phenylalanine inhibition of ALP and the mechanism of ALP activation by taurine as well as its role in endotoxemic injury protection was carried out. Rat intestinal ALP was exposed to taurine, and L-phenylalanine at varying concentrations and periods of time. Substrate concentration-dependent kinetic analysis was carried out at 10 mM concentration of taurine and 5.17mM of p-NPP. The concentration dependent kinetic analysis of L-phenylalanine was also investigated at 60 mM. The partially purified rat intestinal alkaline phosphatase activity was also investigated in the presence of taurine. Their interactive effect on L-phenylalanine inhibition was also analyzed. Investigation of the effect of taurine on rat intestinal ALP hydrolysis of p-NPP revealed that taurine is an activator of intestinal ALP. At 10 mM taurine and 60 mM L-phenylalanine, taurine relieved L-phenylalanine inhibition of rat intestinal ALP. The effect of lipopolysaccharide in the absence and presence of taurine on ALP activity was also carried out in vivo. The kinetic analysis of the data from the in vivo study revealed that rat intestinal ALP activity is higher (12x10-3nmol -1min-1mg protein) in the presence of taurine and LPS when compared with the activity in the presence of LPS (9x10-3nmol-1min-1mg protein) or taurine (8.8x10-3nmol-1min-1mg protein) alone. From this study, it may be concluded that the activation of rat intestinal ALP by taurine may be one of the mechanisms of endotoxemic injury protection.Keywords: Intestinal Alkaline Phosphatase, Taurine, Endotoxemic , Lipopolysaccharid

Produced water treatment technologies

Produced water is a complex mixture of organic and inorganic compounds and the largest volume of by-product generated during oil and gas recovery operations. The potential of oilfield produced water to be a source of fresh water for water-stressed oil-producing countries and the increasing environmental concerns in addition to stringent legislations on produced water discharge into the environment have made produced water management a significant part of the oil and gas business. This article reviews current technologies for the management of produced water, examines how electrochemical techniques may be used in these areas and compares the prospects for future development. It suggests that treatment technologies based on electrochemistry could be the future of produced water management, since produced water is a potential electrolyte because it has a relatively good conductivity. It also explains that by applying photoelectrochemistry, water electrolysis, fuel cell and electrodeposition, electrochemical engineering could achieve energy storage, production of clean water and recovery of valuable metals from produced water with minimal or no negative impact on the environment. © The Author 2012. Published by Oxford University Press

Responses of selected inflammatory, kidney and liver function markers in Serum of Nigerian Children with Severe Falciparum Malaria to treatment with artesunate/artemether-lumefantrine combination therapy

Malaria tolerance is a defence strategy that limits the damage caused by Plasmodium species irrespective of pathogen burden. The mechanisms responsible for this, responses of these mechanisms and their impact on organs to treatment have not been extensively studied. Thus, in this study, serum levels of selected pro- and anti-inflammatory markers, liver and kidney function indices with leucocytes indices in 100 children (1-10 years) with severe falciparum malaria were determined before treatment, at 48 hours during treatment and 48 hours after treatment with WHO recommended dosage of artesunate/artemether-lumefantrine combination therapy using standard methods. Data were analysed using SPSS, differences were considered significant at p<0.05. The results revealed that the serum levels of interleukin-12 (IL-12), interleukin-4 (IL-4), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), C-reactive protein (CRP), nitric oxide (NO), creatinine, albumin, total protein and conjugated bilirubin were not significantly changed at higher parasite densities before treatment. Only serum IL-4, CRP, total bilirubin, urea and creatinine levels and alanine aminotransferase activity were significantly reduced below the ranges of those with severe malaria. The results suggest a self-protective feed-back control, indicating tolerance, which reduced the adverse effects of the disease on kidney and liver functions at higher parasite densities. The results also suggest serum IL-12, IL-4, TNF-α, IFN-γ, CRP and NO levels as immune-protective markers for tolerance and serum IL-4 level as an effective marker for disease severity and recovery from the disease in children with severe malariaKeywords: Immunity, falciparum malaria, inflammatory markers, childrenAfr. J. Biomed. Res. Vol. 22 (May, 2019); 165-17

Distinct Metal Ion Requirements for the Phosphomonoesterase and Phosphodiesterase Activities of Calf Intestinal Alkaline Phosphatase

The roles of Mg2+ and Zn2+ ions in promoting phosphoryl transfer catalysed by alkaline phosphatase are yet to be fully characterised. We investigated the divalent metal ion requirements for the monoesterase and diesterase activities of calf intestinal alkaline phosphatase. The synergistic effect of Mg2+ and Zn2+ in promoting the hydrolysis of para-nitrophenyl phosphate (monoesterase reaction) by alkaline phosphatase is not observed in the hydrolysis of the diesterase substrate, bis-para-nitrophenyl phosphate. Indeed, the diesterase reaction is inhibited by concentrations of Mg2+ that were optimal for the monoesterase reaction. This study reveals that the substrate specificities of alkaline phosphatases and related bimetalloenzymes are subject to regulation by changes in the nature and availability of cofactors, and the different cofactor requirements of the monoesterase and diesterase reactions of mammalian alkaline phosphatases could have significance for the biological functions of the enzymes

Catalytic cofactors (Mg2+ and Zn2+ ions) influence the pattern of vanadate Inhibition of the monoesterase activity of calf intestinal alkaline phosphatase

The mechanism of modulation of vanadate inhibition of alkaline phosphatase activity by catalytic cofactors has not been fully characterized. We investigated the effect of the interaction of catalytic cofactors (Mg2+ and Zn2+) and vanadate (an active site inhibitor) on the rate of hydrolysis of para-nitrophenyl phosphate (pNPP) (monoesterase reaction) by calf intestinal alkaline phosphatase (CIAP). The results showed that vanadate significantly inhibited \u2018cofactor-free\u2019 CIAP, and the inhibition was relieved by the presence of the catalytic cofactors in the reaction. Our results show that the absence of the cofactors did not significantly alter the Km of the reaction, but caused a decrease in the Vmax. Kinetic analyses showed that vanadate inhibited CIAP-catalyzed hydrolysis of pNPP by decreasing the Vmax and increasing the Km of the reaction. The presence of cofactors in the reaction alleviated the effect of vanadate by increasing the Vmax and decreasing the Km. The activity of the dialyzed CIAP was increased by the addition of catalytic cofactors to vanadate-inhibited enzyme. This study provides preliminary data that reversible inhibition of CIAP is subject to the influence of catalytic cofactors. Further studies will reveal detailed mechanistic aspects of this observation and its significance in the biological system

Thermophilic PHP Protein Tyrosine Phosphatases (Cap8C and Wzb) from Mesophilic Bacteria

Protein tyrosine phosphatases (PTPs) of the polymerase and histidinol phosphatase (PHP) superfamily with characteristic phosphatase activity dependent on divalent metal ions are found in many Gram-positive bacteria. Although members of this family are co-purified with metal ions, they still require the exogenous supply of metal ions for full activation. However, the specific roles these metal ions play during catalysis are yet to be well understood. Here, we report the metal ion requirement for phosphatase activities of S. aureus Cap8C and L. rhamnosus Wzb. AlphaFold-predicted structures of the two PTPs suggest that they are members of the PHP family. Like other PHP phosphatases, the two enzymes have a catalytic preference for Mn2+, Co2+ and Ni2+ ions. Cap8C and Wzb show an unusual thermophilic property with optimum activities over 75 °C. Consistent with this model, the activity–temperature profiles of the two enzymes are dependent on the divalent metal ion activating the enzyme