Food for Thought: Enzyme Action

Reactions ◽  
2011 ◽  
Author(s):  
Peter Atkins
Keyword(s):  
Cell Wall ◽  
Specific Enzyme ◽  
Complex Molecules ◽  
Enzyme Action ◽  
Target Molecule ◽  
Fatal Bleeding ◽  
To Come ◽  
Enzyme Molecules ◽  
Essential Contribution ◽  
Chymotrypsin A

Nature makes use of the tools that I have been developing, and does so in the most extraordinary and subtle manner. After all, she has had about four billion years to come up with solutions to problems with which human chemists have striven seriously for only a century or so. Most of the reactions that go on in organisms—including you—are controlled by the proteins called ‘enzymes’ (a name derived from the Greek words for ‘in leaven’, as in yeast). Enzymes are biological catalysts (Reaction 11) that are extraordinarily specific and highly effective in their role. One of these complex molecules might serve as the merest foot soldier in the army of reactions going on inside you, with a role such as severing the bond between two specific groups of atoms in a target molecule. Because their function may be highly specific, enzyme molecules need to be large: they have to recognize the molecule they act on, act on it, then release it so that they can act again. Thus, they have to have several functions built into them. As you will see, enzymes are the ultimate in functional blindness: they feel around in their surroundings in order to identify their substrate, the species they can act on. Life is ultimately blind chemical progress guided by touch. I am going to introduce you to one particular group of enzymes, the ‘proteases’, and focus on one example from this group, namely chymotrypsin. A protease is a traitor to its kind: it is a protein that breaks down other proteins. It plays a role in digestion, of course, but its range is much wider. One protease enables a lucky sperm to eat through the cell wall of an egg and ensure its at least temporary immortality. Another facilitates the clotting of blood to terminate possibly fatal bleeding. Chymotrypsin itself is an enzyme that is secreted from the pancreas into the intestine, and makes an essential contribution to the process of digestion. Its name is derived slightly circuitously from the Greek words for animal fluid, a bodily ‘humour’, and rubbing, as it was obtained as a fluid by rubbing the pancreas.

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 DIATOM AND ITS EXPANDING RESEARCH HORIZON: A REVIEW

2021 ◽  
Vol 21 (no 1) ◽  
Author(s):  
Sanket Anil Bongale ◽  
Shristy Gautam
Keyword(s):  
Cell Wall ◽  
Metabolic Engineering ◽  
Fossil Fuels ◽  
Light Trapping ◽  
Lipid Production ◽  
Vital Role ◽  
Absorption Capacity ◽  
Wastewater Management ◽  
Unique Source ◽  
To Come

Diatoms are the ubiquitous microalgae present all over the world. They are specialized organisms on the planet with the cell wall composed of opaline-silica ornamented with intricate and striked patterns. They are the most prominent as well as successful photosynthetic lower eukaryotes plays a vital role in light trapping. The cell wall nanostructured frustules enhance the light absorption capacity in the multi-layered materials applied as photoanodes. Frustules, the siliceous porous shells of diatoms possess architectures with considerable mechanical strength. Formation of bio-silica shells, optical and fluidic properties along with their flexibility to convert into various nanomaterials have been studied by different biologists, physicists and chemists respectively. In the process of energy generation, conversion and conservation, diatoms play very significant role. Solar fuel is also one of the emerging solutions for increasing future energy demands and to come across this requirement, photocatalysis with the help of diatom’s frustules is mostly preferred. Lipid production in diatoms becomes prior objective for biotechnologists also triggers the work in metabolic engineering since it can be act as an alternative to fossil fuels. Apart from these, the fields like wastewater management also use diatoms as a unique source. The present article inculcates the diverse usage of diatoms in the fields like nanotechnology, biotechnology, environment, biochemistry, biophysics, metabolic engineering and many more. Along with this, the prior focus is on the diatoms as a potential source of nanomaterials, bio-electrolyte and biofuel.

scholarly journals The endeavor of total synthesis and its impact on chemistry, biology and medicine

2014 ◽  
Vol 1 (2) ◽  
pp. 233-252 ◽  
Author(s):  
K. C. Nicolaou ◽  
Christopher R. H. Hale
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Organic Synthesis ◽  
Present State ◽  
Method Development ◽  
Complex Molecules ◽  
Total Syntheses ◽  
Target Molecule ◽  
Living Nature ◽  
Medical Relevance

Abstract The synthesis of urea in 1828 set in motion the discipline of organic synthesis in general and of total synthesis in particular, the art and science of synthesizing natural products, the molecules of living nature. Early endeavors in total synthesis had as their main objective the proof of structure of the target molecule. Later on, the primary goal became the demonstration of the power of synthesis to construct complex molecules through appropriately devised strategies, making the endeavor an achievement whose value was measured by its elegance and efficiency. While these objectives continue to be important, contemporary endeavors in total synthesis are increasingly focused on practical aspects, including method development, efficiency, and biological and medical relevance. In this article, the emergence and evolution of total synthesis to its present state is traced, selected total syntheses from the author's laboratories are highlighted, and projections for the future of the field are discussed.

Abspaltung chemischer Komponenten der Coli-Membran durch daran adsorbierte Phage

1956 ◽  
Vol 11 (6) ◽  
pp. 345-353 ◽  
Author(s):  
G. Koch ◽  
W. Weidel
Keyword(s):  
Cell Membrane ◽  
Host Cell ◽  
Specific Enzyme ◽  
Host Cell Membrane ◽  
Enzyme Action ◽  
Yellow Color

Evidence is brought forth that certain bacteriophages (T2, T4) carry a specific enzyme at their tailtips. It splits chemically defined material off the host cell membrane to which the virus is adsorbed. The splitting reaction can be followed directly and quantitatively by using membranes as a „substrate“ which have been treated with dinitro-fluorobenzene. Dinitrophenyl-residues attached to amino- and other groups of the membrane do not inhibit adsorption and splitting, and splitting-products can be measured colorimetrically on account of their yellow color which also facilitates their isolation. By these means the enzyme action which might be a prerequisite to infection, has been studied to some extent.

scholarly journals Effect of soybean processing on cell wall porosity and protein digestibility

2020 ◽  
Vol 11 (1) ◽  
pp. 285-296 ◽  
Author(s):  
Mostafa Zahir ◽  
Vincenzo Fogliano ◽  
Edoardo Capuano
Keyword(s):  
Cell Wall ◽  
Food Processing ◽  
Protein Digestibility ◽  
Enzyme Action ◽  
Digestion Process ◽  
Protease Enzyme ◽  
Porosity And Permeability ◽  
Soybean Processing ◽  
Soybean Cell ◽  
Cell Wall Porosity

Soybean cell wall porosity and permeability are increased by bio-based food processing and protease enzyme action during the digestion process.

scholarly journals Studies on enzyme action. XIII.—Enzymes of the type

1910 ◽  
Vol 82 (556) ◽  
pp. 349-367 ◽  
Keyword(s):  
Hydrogen Cyanide ◽  
Specific Enzyme ◽  
Enzyme Action ◽  
Milk Sugar ◽  
Previous Communication

In the previous communication of this series (No. XII, 1908, B, Vol. 80, pp. 321—329) the contention was advanced that “emulsin’’prepared from sweet almonds contains at least three distinct enzymes, viz., amygdalase , a β-glucase and gluco-lactase : the first of these, amygdalase, being the enzyme by which amygdalin is resolved into glucose and Fisclier’s glucoside, β -glucase that by which β -glucosides are hydrolysed, gluco-lactase that which hydrolyses milk sugar. Meanwhile the striking discovery has been made by Rosenthaler that emulsin has the property of inducing the formation of dextro-rotatory benzylidenecyanhydrol—such as may be obtained from amygdalin—from benzaldehyde and hydrogen cyanide; this raises the question whether there may not also be present in “emulsin” a specific enzyme capable of operating on the cyanophoric radicle of amygdalin and of resolving it into hydrogen cyanide and benzaldehyde. To avoid periphrasis this hypothetical enzyme may be spoken of as benzcyancise.

Recognition of Symmetry as a Powerful Tool in Natural Product Synthesis

Synthesis ◽  
2021 ◽  
Author(s):  
Corinna S Schindler ◽  
Lara Cala ◽  
Mario A Gaviria ◽  
Scott L Kim ◽  
Trenton R Vogel
Keyword(s):  
Natural Product ◽  
Biological Evaluation ◽  
Natural Product Synthesis ◽  
Complex Molecules ◽  
Active Complex ◽  
Target Molecule ◽  
The Past ◽  
Rapid Access ◽  
Naturally Occurring ◽  
Synthetic Intermediates

The design of concise and efficient synthetic strategies to access naturally occurring, pharmaceutically active complex molecules is of utmost importance in current chemistry. It not only enables rapid access to these molecules and their analogues but also provides sufficient quantities for their biological evaluation. Identification of any symmetric or pseudosymmetric synthetic intermediates upon retrosynthetic bond disconnection of the target molecule holds the promise to significantly streamline the route towards the compound of interest. This review will highlight recent examples of successful natural product syntheses reported within the past five years that benefited from the recognition of symmetry elements during the retrosynthetic design.

Detection of Inactive Enzyme Molecules in Ageing Organisms

2002 ◽  
Vol 2002 (37) ◽  
Author(s):  
Harriet Gershon ◽  
David Gershon
Keyword(s):  
Point Mutations ◽  
Single Amino Acid ◽  
Specific Enzyme ◽  
Functional Protein ◽  
Antigenic Activity ◽  
Protein Molecules ◽  
Immunological Approach ◽  
Enzyme Molecules ◽  
Eventual Death ◽  
Two Populations

Using immunochemical techniques, evidence is obtained that older nematodes ( Turbatrix aceti ) contain two populations of enzyme molecules--one active and the other totally inactive. The synthesis and accumulation of non-functional protein molecules may play a significant part in senescence and the eventual death of organisms. In this communication we report the use of immunological techniques to look directly for the presence of catalytically altered or inactive enzyme molecules in ageing nematodes. The immunological approach is both specific and sensitive and allows for the expression of results in units of catalytic activity per unit of antigenic activity, thus allowing for the detection of partially or totally inactive enzyme molecules present in the form of cross reacting material. This approach has been successfully used in detecting cross reacting protein in bacterial and fungal mutants lacking specific enzyme activities arising from single amino-acid changes caused by point mutations. Reproduced by permission. Harriet Gershon, David Gershon, Detection of Inactive Enzyme Molecules in Ageing Organisms. Nature 227 , 1214-1217 (1970).

Investor-State Dispute Settlement under NAFTA Chapter 11: The Shape of Things to Come?

1998 ◽  
Vol 35 ◽  
pp. 263-290
Author(s):  
J. Anthony VanDuzer
Keyword(s):  
Free Trade Agreement ◽  
Dispute Settlement ◽  
Trade Agreement ◽  
Minimum Standards ◽  
The North ◽  
State Behaviour ◽  
Nafta Chapter 11 ◽  
To Come ◽  
The Right

SummaryRecently, there has been a proliferation of international agreements imposing minimum standards on states in respect of their treatment of foreign investors and allowing investors to initiate dispute settlement proceedings where a state violates these standards. Of greatest significance to Canada is Chapter 11 of the North American Free Trade Agreement, which provides both standards for state behaviour and the right to initiate binding arbitration. Since 1996, four cases have been brought under Chapter 11. This note describes the Chapter 11 process and suggests some of the issues that may arise as it is increasingly resorted to by investors.

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