Cyanide Removal by Chinese Vegetation. Quantification of the Michaelis-Menten Kinetics (6 pp)

Yu, Xiao-Zhang; Zhou, Puhua; Zhou, Xishi; Liu, Yunda

doi:10.1065/espr2005.05.261

Cited by 28 publications

(23 citation statements)

References 19 publications

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“…The similarity of the 10 K M -values indicates that the same enzyme is active in all plants. A similar conclusion was also reached in our previous work during free cyanide metabolism by different plants (Yu et al 2005b). …”

Section: Determination Of Enzyme Kinetics (K M and V Max )supporting

confidence: 80%

Determination of the Michaelis–Menten kinetics and the genes expression involved in phyto-degradation of cyanide and ferri-cyanide

Zhang

2016

Ecotoxicology

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Hydroponic experiments were conducted with different species of plants (rice, maize, soybean and willow) exposed to ferri-cyanide to investigate the half-saturation constant (K M ) and the maximal metabolic capacity (v max ) involved in phyto-assimilation. Three varieties for each testing species were collected from different origins. Measured concentrations show that the uptake rates responded biphasically to ferri-cyanide treatments by showing increases linearly at low and almost constant at high concentrations from all treatments, indicating that phyto-assimilation of ferri-cyanide followed the Michaelis-Menten kinetics. Using non-linear regression, the highest v max was by rice, followed by willows. The lowest v max was found for soybean. All plants, except maize (DY26) and rice (XJ12), had a similar K M value, suggesting the same enzyme was active in phyto-assimilation of ferri-cyanide. Transcript level, by real-time quantitative PCR, of enzymes involved in degradation of cyanides showed that the analyzed genes were differently expressed during different cyanides exposure. The expression of CAS and ST genes responded positively to KCN exposure, suggesting that β-CAS and ST pathways were two possible pathways for cyanide detoxification in rice. The transcript level of NIT and ASPNASE genes also showed a remarkable up-regulation to KCN, implying the contribution to the pool of amino acid aspartate, which is an end product of CN metabolism. Up-regulation of GS genes suggests that acquisition of ammonium released from cyanide degradation may be an additional nitrogen source for plant nutrition. Results also revealed that the expressions of these genes, except for GS, were relatively constant during iron cyanide exposure, suggesting that they are likely metabolized by plants through a non-defined pathway rather than the β-CAS pathway.

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Section: Determination Of Enzyme Kinetics (K M and V Max )supporting

confidence: 80%

Determination of the Michaelis–Menten kinetics and the genes expression involved in phyto-degradation of cyanide and ferri-cyanide

Zhang

2016

Ecotoxicology

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“…Yu et al (2004) found for weeping willow Salix babylonica L. a removal capacity of 6.08 mg CN/(kg·h) with an initial concentration in solution of 0.94 mg CN/L in the test with detached leaves in a closed bottle. The same test was performed with varying concentrations in solution (0.49; 1; 2.07; 7.59 mg CN/L) to determine the Michaelis-Menten parameters (Yu et al 2005b). For Salix babylonica L., the removal rate at 1.0 mg CN/L was 4.1 mg CN/(kg·h), while v max was 9.57 to 12.76 mg CN/(kg·h).…”

Section: Discussionmentioning

confidence: 99%

“…All species were found to metabolize cyanide, but with different velocity. Data on the Michaelis-Menten kinetics (half-saturation constant K M and maximal removal rate v max ) of cyanide removal for 12 plant species out of 9 families was determined using excised leaf tissues (Yu et al, 2005b). Values of v max and K M were found in a range between 6.68 and 21.91 mg CN/(kg·h) and 0.90 to 3.15 mg CN/L, respectively.…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature on the Uptake and Metabolism of Cyanide by Weeping Willows

Trapp

Zhou

et al. 2007

International Journal of Phytoremediation

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“…Despite a significant enrichment in the 15 N content of the plant materials, negligible cyanide was tracked in any part of the plant tissues, indicating that applied free cyanide was metabolized by plants. Larsen et al (2004) determined the metabolic capacity of five Danish woody plants (willow, poplar, elder, rose and birch) for cyanide and found that the removal rates followed the Michaelis-Menten kinetics, where realistic values of the half-saturation constant, K M , were around 1.5 mg CN/L; the maximum metabolic capacity, v max , was between 9.3 and 14.5 mg CN/kg FW h. The Michaelis-Menten kinetics of cyanide removal was also determined for 12 Chinese plant species out of 9 families (Table 1), where values of K M were found in a range between 0.90 and 3.15 mg CN/L, and the values of v max were normally distributed with a mean of 13 mg CN/ kg h using nonlinear regression treatments (Yu et al 2005b). Additionally, differences in Michaelis-Menten kinetics for different cultivars of maize during cyanide removal were determined using the same exposure regime .…”

Section: Uptake and Transport Of Cyanide By Plantsmentioning

confidence: 99%

Uptake, assimilation and toxicity of cyanogenic compounds in plants: facts and fiction

2014

Int. J. Environ. Sci. Technol.

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Cyanide is a simple nitrogenous compound that arises from both anthropogenic and natural sources. Plants vary considerably in their physiological and biochemical responses to different species of exogenous cyanides from reduced growth to inhibition on enzymatic activities. Also, great differences in uptake, assimilation and toxicity between free cyanide and iron cyanide have been observed. Unlike botanical uptake of free cyanide chiefly achieved by simple diffusion, iron cyanides have long been considered membrane impermeable and a protein-mediated uptake mode has been proposed. Biological fate of cyanides in plant materials is highly dependent on speciation of cyanides present. Natural development of degradation of free cyanide in plants is very obvious, where the b-cyanoalanine pathway has been widely distributed in higher plants and the production of asparagine and aspartate associated with cyanide assimilation is suggestive. Because phytodissociation of iron cyanides into free cyanide in plant materials is not a mandatory process involved in phytoassimilation, plants probably metabolized them through an undiscovered degradation pathway rather than the b-cyanoalanine pathway. Available information shows phytoassimilation of endogenous cyanide into nitrogen metabolism; however, additional efforts to fully elucidate presence of essential enzymes involved and their proteomic or DNA expression quantitatively are needed to prove and clarify phyto-benefits of assimilation of exogenous cyanide in plant nutrition.

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Cyanide Removal by Chinese Vegetation. Quantification of the Michaelis-Menten Kinetics (6 pp)

Cited by 28 publications

References 19 publications

Determination of the Michaelis–Menten kinetics and the genes expression involved in phyto-degradation of cyanide and ferri-cyanide

Determination of the Michaelis–Menten kinetics and the genes expression involved in phyto-degradation of cyanide and ferri-cyanide

Effect of Temperature on the Uptake and Metabolism of Cyanide by Weeping Willows

Uptake, assimilation and toxicity of cyanogenic compounds in plants: facts and fiction

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