Thermokinetic study on the reversible competitive inhibition of bovine liver arginase

Xie, Xianhong; Wang, Cunxin; Wang, Zhiyong

doi:10.1002/cjoc.20040221109

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…L-Ornithine formation may be the main function of arginase in cells that have incomplete urea cycles. 4 In the previous work, we have studied the inhibition of arginase by product, 5 L-lysine, 6 and sodium fluoride, 7 and the activation of arginase by manganese ions has been also studied. 8 In the present work, the influence of glycine on bovine liver arginase activity, Michealis constant (K m ), maximum velocity (V m ), inhibition constant of product (K p ), was studied by thermokinetics.…”

Section: Introductionmentioning

confidence: 99%

Thermokinetic Studies on the Activation of Arginase by Glycine

Xie¹,

Wang

2010

Chin. J. Chem.

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The activation of bovine liver arginase, which catalyzes the hydrolysis of L-arginine to L-ornithine and urea, by glycine was studied by thermokinetic methods at 37 ℃ in 40 mmol•L -1 sodium barbiturate-HCl buffer solution (pH 9.4). Results of this experiment indicate that an appropriate concentration of glycine can enhance the activity of arginase, and the relative activation rate reached its maximum value, 74%, when the concentration of glycine in reaction system was 1 mmol•L -1 and the initial concentration of arginine was 5 mmol•L -1 . With the increase of substrate concentration, the relative activation rate decreased in a definite glycine concentration. Michealis constant K m of reaction decreased from 5.53 to 3.31 mmol•L -1 and inhibition constant of product L-ornithine K p increased from 1.18 to 3.73 mmol•L -1 when glycine concentration was 1 mmol•L -1 . For these reasons one possible activation mechanism of arginase by glycine was suggested that the activation effect results from the competition of glycine and arginine to enzyme activity position. When one or two of the activity positions of arginase are occupied by glycine, it is propitious for the enzyme to complex with substrate and obstruct L-ornithine from combining with enzyme, and when all of the activity positions are occupied by glycine, the activation effect vanishs and the inhibition effect appears.

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Section: Introductionmentioning

confidence: 99%

Thermokinetic Studies on the Activation of Arginase by Glycine

Xie¹,

Wang

2010

Chin. J. Chem.

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Rapid Detection of Irreversible Acetylcholineasterase Inhibitor by Mass Spectrometry Assay

et al. 2012

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Here we developed a rapid method to detect acetylcholinesterase (AChE) activity by matrix‐assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI‐FTMS) for screening irreversible AChE inhibitors. Due to its good salt‐tolerance and low sample consumption, MALDI‐FTMS could facilitate rapid detection, especially detection in real application. AChE activity was determined through calculating abundance of substrate and product in mass spectrometry. By this approach, we investigated the relation of organophosphorous (OP) concentrations and AChE inhibition. Shown in different inhibition curves from different OP pesticides, enzyme inhibitions still kept good correlation with concentration of OPs. Finally, this AChE‐inhibited method was applied to screen whole bloods of four decedents and discuss their death reason. In contrast to healthy persons, three of decedents showed low AChE activity, and probably died for irreversible AChE inhibitors. Through the following detecting in GC‐MS/MS, the possible death reason of these three decedents was confirmed, and another decedent actually died for sumicidin, a non‐AChE inhibitor. It demonstrated that screening irreversible AChE inhibitors by detecting enzyme activity in MALDI‐FTMS provided fast and accurate analysis results and excluded another toxicants not functioning on AChE. This method offered alternative choices for indicating the existence of enzyme inhibitors.

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Thermokinetic study on the reversible competitive inhibition of bovine liver arginase

Cited by 2 publications

References 15 publications

Thermokinetic Studies on the Activation of Arginase by Glycine

Thermokinetic Studies on the Activation of Arginase by Glycine

Rapid Detection of Irreversible Acetylcholineasterase Inhibitor by Mass Spectrometry Assay

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