Inhibition of paraoxonase activity in human liver microsomes by exposure to EDTA, metals and mercurials

Gonzálvo, M. Carmen; Gil, Fernando; Hernández, Antonio F.; Villanueva, Enrique; Pla, Antonio

doi:10.1016/s0009-2797(97)00046-x

Cited by 92 publications

(60 citation statements)

References 13 publications

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“…With regard to the inhibition of PON1, previous studies showed that the arylesterase or paraoxonase activity of PON1 was inhibited by divalent metal ions, phosphate compounds, or fatty acids (18,34,51,52). However, there has been no report concerning the substrate-specific inhibition of PON1 activity.…”

Section: Discussionmentioning

confidence: 99%

Preferential inhibition of paraoxonase activity of human paraoxonase 1 by negatively charged lipids

Nguyen

Sok

2004

Journal of Lipid Research

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To determine the causes responsible for a preferential decrease of paraoxonase activity, which has been observed in the serum of patients with cardiovascular diseases, the inactivation or inhibition of paraoxonase 1 (PON1) by various endogenous factors was examined using paraoxon or phenyl acetate as a substrate. When purified PON1 was incubated with various endogenous oxidants or aldehydes, they failed to cause a preferential reduction of paraoxonase activity, suggesting no participation of the inactivation mechanism in the preferential loss of paraoxonase activity. Next, when we examined the inhibition of PON1 activity by endogenous lipids, monoenoic acids such as palmitoleic acid or oleic acid inhibited paraoxonase activity preferentially, in contrast to a parallel inhibition of both activities by polyunsaturated or saturated acids. Noteworthy, oleoylglycine inhibited paraoxonase activity, but not arylesterase activity, complying with the selective inhibition of paraoxonase activity. Moreover, such a selective inhibition of paraoxonase activity was also expressed by lysophosphatidylglycerol or lysophosphatidylinositol, but not by lysophosphatidylserine or lysophosphatidylcholine, indicating the importance of the type of head group. Furthermore, such a preferential or selective inhibition of paraoxonase activity was also observed with PON1 associated with HDL or plasma. These data suggest that some negatively charged lipids may correspond to factors causing the preferential inhibition of paraoxonase activity of PON1.

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Section: Discussionmentioning

confidence: 99%

Preferential inhibition of paraoxonase activity of human paraoxonase 1 by negatively charged lipids

Nguyen

Sok

2004

Journal of Lipid Research

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“…Subsequent studies with rat and human liver PON1 demonstrated many biochemical characteristics in common with those of serum PON1. These included optimum pH, substrate affinity (KM), kinetic constants, heat inactivation, and calcium requirement [25] ; all of which strongly suggested a high degree of identity between both enzymes.…”

Section: Pon1 Is Essentially Synthesized By the Livermentioning

confidence: 99%

Measurement of serum paraoxonase-1 activity in the evaluation of liver function

Camps¹,

Marsillach²,

Joven³

2009

WJG

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Paraoxonase-1 (PON1) is an esterase and lactonase synthesized by the liver and found in the circulation associated with high-density lipoproteins. The physiological function of PON1 seems to be to degrade specific oxidized cholesteryl esters and oxidized phospholipids in lipoproteins and cell membranes. PON1 is, therefore, an antioxidant enzyme. Alterations in circulating PON1 levels have been reported in a variety of diseases involving oxidative stress including chronic liver diseases. Measurement of serum PON1 activity has been proposed as a potential test for the evaluation of liver function. However, this measurement is still restricted to research and has not been extensively applied in routine clinical chemistry laboratories. The reason for this restriction is due to the problem that the substrate commonly used for PON1 measurement, paraoxon, is toxic and unstable. The recent development of new assays with non-toxic substrates makes this proposal closer to a practical development. The present editorial summarizes PON1 biochemistry and function, its involvement with chronic liver impairment, and some aspects related to the measurement of PON1 activity in circulation.

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“…Kinetic analysis (Lineweaver-Burk and Dixon plots) indicated that different inhibitors exhibit different inhibition patterns, as EDTA showed competitive inhibition (11). To investigate the effect of inhibitors on enzyme activity, Ethylene Diamine Tetra Acetic acid (EDTA) was prepared at a concentration of 1mg/ml and added in different concentrations (0.538 mM, 1.07 mM, 1.61 mM, 2.15 mM and 2.69 mM) to the assay mixture and measured the amylase activity.…”

Section: Effect Of Inhibitormentioning

confidence: 99%

Comparative study on production of α-Amylase from Bacillus licheniformis strains

Divakaran¹,

Chandran²,

Chandran³

2011

Braz. J. Microbiol.

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Alpha amylase (α-1, 4-glucan-glucanhydrolase, EC 3.2.1.1), an extracellular enzyme, degrades α, 1-4 glucosidic linkages of starch and related substrates in an endo-fashion producing oligosaccharides including maltose, glucose and alpha limit dextrin (7). The present study deals with the production and comparative study of production of α-amylase from two strains of Bacillus licheniformis, MTCC 2617 and 2618, by using four different substrates, starch, rice, wheat and ragi powder as carbon source by submerged fermentation. The effect of varying pH and incubation temperature, activator, inhibitor, and substrate concentration was investigated on the activity of α-amylase produced by MTCC strain 2618. The results shows that the production of the α-amylase by the B.licheniformis strain MTCC 2618, using four different substrates were found to be maximum (Starch 3.64 IU/ml/minutes, Rice powder 2.93 IU/ml/minutes, Wheat powder 2.67 IU/ml/minutes, Ragi powder 2.36 IU/ml/minutes) on comparing the enzyme production of two strains. It was also observed that the maximum production was found on the 3 rd day (i.e. 72 hr) and characterization of crude enzyme revealed that optimum activity was at pH 7 and 37°C.

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Inhibition of paraoxonase activity in human liver microsomes by exposure to EDTA, metals and mercurials

Cited by 92 publications

References 13 publications

Preferential inhibition of paraoxonase activity of human paraoxonase 1 by negatively charged lipids

Preferential inhibition of paraoxonase activity of human paraoxonase 1 by negatively charged lipids

Measurement of serum paraoxonase-1 activity in the evaluation of liver function

Comparative study on production of α-Amylase from Bacillus licheniformis strains

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