scholarly journals Regulation of plant cell-wall pectin methyl esterase by polyamines - Interactions with the effects of metal ions

1992 ◽  
Vol 205 (2) ◽  
pp. 711-714 ◽  
Author(s):  
Dominique CHARNAY ◽  
Joannes NARI ◽  
Georges NOAT
Keyword(s):  
Cell Wall ◽  
Metal Ions ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Pectin Methyl Esterase

scholarly journals Pectin methylesterase, metal ions and plant cell-wall extension. Hydrolysis of pectin by plant cell-wall pectin methylesterase

1991 ◽  
Vol 279 (2) ◽  
pp. 343-350 ◽  
Author(s):  
J Nari ◽  
G Noat ◽  
J Ricard
Keyword(s):  
Cell Wall ◽  
Metal Ions ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Direct Interaction ◽  
Enzyme Reaction ◽  
Pectin Methylesterase ◽  
High Concentrations ◽  
Enzyme Molecules ◽  
Hydrolysis Of

The hydrolysis of p-nitrophenyl acetate catalysed by pectin methylesterase is competitively inhibited by pectin and does not require metal ions to occur. The results suggest that the activastion by metal ions may be explained by assuming that they interact with the substrate rather than with the enzyme. With pectin used as substrate, metal ions are required in order to allow the hydrolysis to occur in the presence of pectin methylesterase. This is explained by the existence of ‘blocks’ of carboxy groups on pectin that may trap enzyme molecules and thus prevent the enzyme reaction occurring. Metal ions may interact with these negatively charged groups, thus allowing the enzyme to interact with the ester bonds to be cleaved. At high concentrations, however, metal ions inhibit the enzyme reaction. This is again understandable on the basis of the view that some carboxy groups must be adjacent to the ester bond to be cleaved in order to allow the reaction to proceed. Indeed, if these groups are blocked by metal ions, the enzyme reaction cannot occur, and this is the reason for the apparent inhibition of the reaction by high concentrations of metal ions. Methylene Blue, which may be bound to pectin, may replace metal ions in the ‘activation’ and ‘inhibition’ of the enzyme reaction. A kinetic model based on these results has been proposed and fits the kinetic data very well. All the available results favour the view that metal ions do not affect the reaction through a direct interaction with enzyme, but rather with pectin.

scholarly journals Pectin methylesterase, metal ions and plant cell-wall extension. The role of metal ions in plant cell-wall extension

1991 ◽  
Vol 279 (2) ◽  
pp. 351-354 ◽  
Author(s):  
A M Moustacas ◽  
J Nari ◽  
M Borel ◽  
G Noat ◽  
J Ricard
Keyword(s):  
Cell Wall ◽  
Metal Ions ◽  
Plant Cell ◽  
Electrostatic Potential ◽  
Metal Ion ◽  
Plant Cell Wall ◽  
Pectin Methylesterase ◽  
Ion Concentration ◽  
Cell Wall Extension ◽  
Wall Loosening

The study of pectin methylesterase and wall-loosening enzyme activities in situ, as well as the estimation of the electrostatic potential of the cell wall, suggest a coherent picture of the role played by metal ions and pH in cell-wall extension. Cell-wall growth brings about a decrease of local proton concentration because the electrostatic potential difference (delta psi) of the wall decreases. This in turn activates pectin methylesterase, which restores the initial delta psi value. This process is amplified by the attraction of metal ions in the polyanionic cell-wall matrix. The amplification process is basically due to the release of enzyme molecules that were initially bound to ‘blocks’ of carboxy groups. This increase of metal-ion concentration also results in the activation of wall-loosening enzymes. Moreover, the apparent ‘inhibition’ of pectin methylesterase by high salt concentrations may be considered as a device which prevents the electrostatic potential from becoming too high.

scholarly journals Pb induces plant cell wall modifications - in particular - the increase of pectins able to bind metal ions level

2013 ◽  
Vol 1 ◽  
pp. 26008 ◽  
Author(s):  
M. KrzesВowska ◽  
I. Rabęda ◽  
M. Lewandowski ◽  
S. Samardakiewicz ◽  
A. Basińska ◽  
...  
Keyword(s):  
Cell Wall ◽  
Metal Ions ◽  
Plant Cell ◽  
Plant Cell Wall

Ultrasound Assisted Solid-Liquid Extraction Devices - Harnessing Active Ingredients from Plant materials – Overview and Analysis

2020 ◽  
Vol 13 ◽  
Author(s):  
Venkatasubramanian Sivakumar
Keyword(s):  
Mass Transfer ◽  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Liquid Extraction ◽  
Active Ingredients ◽  
Plant Materials ◽  
Ultrasound Assisted ◽  
Solid Liquid Extraction ◽  
Solid Liquid

Background: In the growing environmental concern use of natural products, efficient processes and devices are necessary. Solid-Liquid extraction of active Ingredients from Plant materials is one of the important unit operations in Chemical Engineering and need to be enhanced. Objectives: Since, these active ingredients are firmly bound to the plant cell wall membrane, which pose mass-transfer resistance and need to get detached through the use of suitable process intensification tools such as ultrasound and suitable devices. Therefore, detailed analysis and review is essential on development made in this area through Publications and Patents. Hence, the present paper illustrates the development of ultrasound assisted device for solid-liquid extraction are presented in this paper. Methods: Advantages such as % Yield, Reduction in extraction time, use of ambient conditions, better process control, avoidance or minimizing multi stage extraction could be achieved due to the use of ultrasound in extraction as compared to conventional processes. Conclusions: Use of ultrasound to provide significant improvements in the extraction of Vegetable tannins, Natural dyes for application in Leather processing has been demonstrated and reported earlier. These enhancement could be possible through various effects of ultrasound such as better flow of solvents through micro-jet formation, mass transfer enhancement due to rupture of plant cell wall membranes through acoustic cavitation, better leaching due to micro-mixing and acoustic streaming effects. This approach would minimize material wastage; thereby, leading to eco-conservation of plant materials, which is very much essential for better environment. Hence, various methods and design for application of ultrasound assisted solid-liquid extractor device are necessary.

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