Overview
FrançaisABSTRACT
Enzymes are able to compensate their lack of genericity by their extraordinary selectivity and even enantioselectivity or regioselectivity. Due to these properties, they are valuable tools in order to carry out synthesis reactions under conditions which are particularly compatible with the preservation of the environment (aqueous medium, non-extreme pH, low temperatures). The increasing usage of renewable raw materials thus of biologic origin in order to foster sustainable development conditions will certainly increase the cases of implementation of biocatalysts. Furthermore, the molecular biology tools combined with structural biology and in silico modeling tools currently allow not only for the diversification of the sources of new enzymes and a massive improvement of their efficiency and stability, but also the creation of completely original biocatalysts which are able to carry out new reactions.
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Read the articleAUTHORS
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Didier COMBES: Professor at the Institut national des sciences appliquées de Toulouse
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Pierre MONSAN: Professor at the Institut national des sciences appliquées de Toulouse - École nationale supérieure des mines de Paris - University Institute of France
INTRODUCTION
Enzymes are able to compensate for their lack of genericity through their extraordinary selectivity, and even enantioselectivity and regioselectivity, making them the tools of choice for carrying out synthesis reactions under conditions that are particularly compatible with environmental preservation (aqueous media, non-extreme pH, low temperatures). The ever-increasing use of renewable raw materials, i.e. of biological origin, to promote conditions of sustainable development can only increase the number of examples of biocatalyst applications. What's more, the tools of molecular biology, combined with those of structural biology and "in silico" modelling, now make it possible not only to diversify the sources of new enzymes and extraordinarily improve their efficiency and stability, but also to design totally original biocatalysts capable of carrying out new reactions.
It is very difficult to give an exact date for the discovery of enzymes. Activity outside a living cell was observed in 1783, when Spallanzani noted that meat was "liquefied" by the gastric juices of falcons.
Similar observations were subsequently made, but the first discovery of an enzyme is generally credited to Payen and Persoz, who in 1833 treated an aqueous extract of malt with ethanol, precipitating a heat-labile substance that initiates starch hydrolysis. They called this fraction "diastase". Today, we know that diastase was an impure preparation of amylase.
The word enzyme, Greek for "in yeast", first appeared in 1878: Kühne used it to distinguish between "organized ferments" (the whole micro-organism) and "inorganized ferments" (excreted by micro-organisms).
It was in 1897 that Bertrand observed that some enzymes required dialyzable factors for catalytic activity: these substances were called coenzymes.
From the early 20th century onwards, numerous attempts were made to purify enzymes and describe their catalytic activity in precise mathematical terms.
In 1902, Henri suggested that an enzyme-substrate complex was an obligatory intermediate in the catalytic reaction. He also gave a mathematical equation that took into account the effect of substrate concentration on reaction rate.
The effect of pH on enzyme activity was first demonstrated by Sorensen in 1909, and it was in 1913 that Michaelis and Menten rediscovered Henri's equation. This equation is based on simple principles of chemical equilibrium.
The fact that enzymes are proteins was not accepted until the late 1920s.
Finally, in 1965, Monod, Wyman and Changeux presented a kinetic model for allosteric enzymes (regulatory enzymes...
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Bibliography
Websites
Enzyme nomenclature http://www.chem.qmul.ac.uk/iubmb/
Classification CAZy (Carbohydrate Active enZymes) http://www.cazy.org/
Enzyme Information System http://www.brenda-enzymes.org/index.php4
...Regulations
Food enzymes http://europa.eu/scadplus/leg/fr/lvb/l21036.htm
Manufacturers – Suppliers – Distributors
Association of Enzyme Producers and Formulators: AMFEP http://www.amfep.org/
Enzyme suppliers
NOVOZYMES A/S http://www.novozymes.com/
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