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List Of Enzymes And Their Functions Pdf

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Function: Amylase is an enzyme that is responsible for the breaking of the bonds in starches, polysaccharides, and complex carbohydrates to be turned into simple sugars that will be easier to absorb.

Enzyme , a substance that acts as a catalyst in living organisms, regulating the rate at which chemical reactions proceed without itself being altered in the process.

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Soil Sci. Plant Nutr. Rao, R. Scelza, R. Scotti and L. Environmental pollution is growing more and more due to the indiscriminate and frequently deliberate release of hazardous, harmful substances. Research efforts have been devoted to develop new, low-cost, low-technology, eco-friendly treatments capable of reducing and even eliminating pollution in the atmosphere, the hydrosphere and soil environments. Among biological agents, enzymes have a great potentiality to effectively transform and detoxify polluting substances because they have been recognized to be able to transform pollutants at a detectable rate and are potentially suitable to restore polluted environments.

This brief review will examine some classes of pollutants and enzymes capable of transforming them effectively into innocuous products. Particular attention will be devoted to pollutants with a high polluting potential such as polyphenols, nitriles, PAHs, cyanides and heavy metals. The enzymatic processes developed and implemented in some of these detoxification treatments will be examined in details.

The main advantages as well as the main drawbacks that are still present in the extensive application of enzymes in the in situ restoration of polluted environments will be discussed. Keywords: Pollutants, enzymes, environmental pollution, bioremediation.

Several substances with high polluting potential are present in the environment and affect soil, sediments, water, air, microbial organisms, plants, animals, and humans. They may be distributed in one or all environmental compartments. A list of the most common and widespread pollutants is shown in Figure 1. Polluting substances are very often present not only as mixtures of different organic compounds but also of organic and inorganic ones.

The origins and sources of pollution are different: industrial activities such as mining and metal processing, petrochemical and industrial complexes, industry effluents, chemical weapons production, pulp and paper industries, dye industries and industrial manufacturing; and anthropogenic activities such as traffic, agricultural practices, and others. Pollutants may affect the health of humans, animals and environments for several causes. They may inhibit respiration. They may provoke a reduced reproduction of fish-eating birds as well as contribute to the birth of premature babies or children with genetic defects such as downs syndrome, anencephaly,and spina bifida.

They may destruct reproduction in humans and animals, may have carcinogen and teratogenic effects on humans, and may give rise to arsenicosis and related damages. Almost all regions of the world have different and widespread types of pollutants and pollutant sources, i.

Most of these areas are located in poor countries where pollution continues to be a major cause of death, illness and long-term damage. Also Western Europe is not free from environmental pollution. Table 1 reports an inventory of polluted sites in Western Europe dated in Gianfreda and Greco unpublished results. More than , polluted sites have been identified in developed countries such as Germany. In the Netherlands, , polluted sites have been estimated, though most of them have not been identified yet.

These numbers give an idea of the enormous magnitude of pollution in the environment. And it could be said that a large part or even the entire earth is polluted. As the increase of contaminated sites poses a major environmental and human health problem, it appears mandatory to decontaminate the environment and to implement efficient decontamination strategies.

The main goals of decontamination should be recovery of soil health and fertility, detoxification of ground-water, reutilization of wastewater mainly in countries with severe water deficiency , removal of negative effects on human and animal health, and production of healthy air. Therefore, a growing interest is being devoted to the search of effective remediation technologies for partial or total recovery of polluted sites.

The nature of the contaminant sources and the co-occurrence of organic and inorganic compounds often make their remediation problematic. Several methodologies have been applied for the remediation of polluted systems and many of them, when implemented in the target sites, have led to successful results. Two basic strategies have been utilized: engineering and biological ones Bollag and Bollag, Engineering strategies are basically founded on physical and chemical methods, whereas biological strategies require the involvement of biological agents Gianfreda and Rao, Composting, land fanning, bioreactors, bioremediation, and phytoremediation are the main biological methods applicable to soil and groundwater.

Land fanning is not suitable for the latter. Regardless the adopted method, the decontamination of polluted sites may be carried out by in-situ if soils and water are treated directly on site or ex-situ if they are excavated, transported to another site and, then treated treatments. In situ techniques are usually less expensive and involve less physical treatments, whereas ex situ treatments require higher costs and an increased environmental disturbance.

Bioremediation and phytoremediation appear now as appealing technologies being based on the use of living organisms, microorganisms, plants, and their enzymatic set. The use of enzymatic proteins may represent a good alternative for overcoming most disadvantages related to the use of microorganisms Nannipieri and Bollag, ; Karam and Nicell, ; Nicell, ; Gianfreda and Bollag, , Gianfreda and Rao, Enzymes have several beneficial characteristics.

They are the main effectors of all the transformations occurring in the biota. They are catalysts with either narrow chemo-, region- and stereo-selectivity or broad specificity and, therefore, they can be applied to a large range of different compounds in mixture, as well.

They may produce extensive transformations of structural and toxicological properties of contaminants, and even their complete conversion into innocuous inorganic end products. They may perform processes for which no efficient chemical transformations have been devised. Moreover, enzymes may present advantages over traditional technologies, and also over microbial remediation.

Indeed, enzymes are not inhibited by inhibitors of microbial metabolism. They can be used under extreme conditions limiting microbial activity. They are effective at low pollutant concentrations and are active in the presence of microbial predators or antagonists. They act against a given substrate microorganisms may prefer more easily degradable compounds than the pollutant , and are more mobile than microorganisms because of their smaller size Gianfreda and Bollag, All these characteristics render enzymes eco-friendly catalysts as well as enzymatic techniques environmentally friendly processes.

These latter may have the capability of remediation of many compounds that are unfriendly to the environment by the present ecological standards of our societies. As claimed by Alcade et al, , biocatalysis by enzymes very often known as white biotechnology "fully participates in the "green chemistry" concept introduced in the 90s by Sheldon and van Rantwijk, , and its effect on sustainability is now established beyond question". Enzymes may act intracellularly, i.

Recently, very interesting examples of structures and methods for immobilization of biomolecules, including enzymes, were illustrated by Rodriguez Couto and Toca Herrera with specific reference to lacease, an enzyme very often used in decontamination of pollutants Gianfreda et al, Both 2D and 3D supramacromolecular structures can be used to immobilize biomolecules or to build microreactors Figure 2.

The most representative enzymatic classes in the remediation of polluted environments are: hydrolases, dehalo-genases, transferases and oxidoreductases. Their main producers are bacteria, fungi, mainly white-rot fungi, plants and microbe-plant associations.

For many of these enzymes the transformation of different xenobiotic substances has been tested mainly under laboratory conditions. Reagents and activity assay conditions are available for many of these enzymes, and they are described in detail to allow their easy detection and application Whiteley and Lee, Examples of hydrolases are phosphotriesterases, anudases, proteases, carbohydrases cellulases and amylases , depolymerase.

Mono- or di-oxygenases, reductases, dehalogenases, cytochrome P monoxygenases, phenoloxidases laceases, tyrosinases and peroxidases lignin and manganese peroxidases are the main classes of oxidoreductases. The breakdown of esteric, amidic and peptidic bonds by esterases, anudases and proteases may lead to products with little or no toxicity. For instance, bacterial hydrolases such as carbamate or parathion hydrolases from Achromobacter, Pseudomonas, Flavobacterium, Nocardia, and Bacillus cereus have been successfully used in the transformation of pollutants such as carbofuran and carbaryl or parathion, diazinon and coumaphos Coppella et al, ; Mulbry, and Eaton, ; Sutherland et al.

Similarly, carbohydrases, depolymerases, proteases and phosphatases, produced by several bacteria and fungi, can be suitable for the transformation of insoluble materials such as carbohydrates, plastics and proteins van Wyk, , Nakamura et al, ; Singh, Sornyotha et al. Moreover, this method could be used in the low-cyanide-cassava starch production and is suitable for detoxification of cassava products during processing.

Figure 2. Supramacromolecular structures usable to immobilize biomolecules. For details see the text From Rodriguez Couco and Herrera, An interesting role is played by a class of enzymes involved in the transformation of nitrile compounds Banerjee et al, ; Singh et al, The prefix cyano is used in chemical nomenclature to indicate the presence of a nitrile group in a molecule.

A cyanide ion is a negative ion with the formula CN -. The -CN group is sometimes, less properly, referred to as a cyanide group or cyano group, and compounds with it are sometimes referred to as cyanides. Many cyanide-containing compounds are highly toxic and deadly poisonous while some nitriles which do not release cyanide ions may have low toxicities.

Nitrile compounds are synthesized by plants, fungi, bacteria, algae, insects and sponges. There are two different enzymatic pathways for the degradation of nitrile compounds Figure 3. The other is the direct hydrolysis of nitriles to the corresponding acids and ammonia, catalyzed by nitrilase.

Nitrilases EC 3. They are produced by both bacteria, such as Nocardia sp. Some of the nitrilases are capable of hydrolyzing nitriles stereospecifically. While much information is available on the structure and function of bacterial nitrilases Banerjee et al, ; Singh et al, , a lesser amount of findings is available for nitrilases from filamentous fungi.

In particular, they investigated the potentiality of fungal nitrilase and compared their performance with some from bacterial origins. Their studies established that the nitrilases of filamentous fungi have high relative activities toward hetero aromatic nitriles, and accept a wide range of aliphatic and alicyclic nitriles. One of the benefits of fungal nitrilases is their high specific activity toward substances such as benzonitrile and analogues, 3- and 4-cyanopyridine and also some medium chain length aliphatic nitriles, considered their preferential substrates.

For instance, A. The biotechnological impact of nitrilases lies in their potential to accept a wide range of aliphatic and aclicyclic nitriles; to hydrolyze nitriles under mild conditions, with excellent regio- and enantioselectivities in some cases; to exhibit high activity, stability and thermo-stability.

This makes these enzymes good candidates for biodegraders of nitrile contaminants. Hydrogen cyanide HCN is a major environmental pollutant of the chemical and metallurgical industries. It is produced on large scale worldwide to satisfy major industrial countries needs. Cyanide is extremely toxic to aerobic forms of life since it inhibits respiration by strongly binding to cytochrome oxidase Solomonson, Although extremely toxic, cyanide can enzymatically be converted to the less toxic thiocyanate by rhodaneses thiosulfatexyanide sulfurtransferases, EC 2.

A genetic system was engineered to express high levels of recombinant Pseudomonas aeruginosa rhodanese r-RhdA in E. The accessibility of thiosulfate to r-RhdA limited the sulfur transfer reaction in the cellular system, but permeabilization of the bacterial membrane increased the cyanide conversion into thiocyanate.

Overall results indicated that engineered E. An important group of enzymes is constituted by oxidative enzymes Gianfreda et al, ; Duran and Esposito, ; Torres et al, ; Gianfreda and Rao, ; Gianfreda et al, ; Rodriguez Couto and Toca Herrera,

Enzymes: How they work and what they do

Enzymes help speed up chemical reactions in the human body. They bind to molecules and alter them in specific ways. They are essential for respiration, digesting food, muscle and nerve function, among thousands of other roles. In this article, we will explain what an enzyme is, how it works, and give some common examples of enzymes in the human body. Enzymes are built of proteins folded into complicated shapes; they are present throughout the body.

Enzymes help speed up chemical reactions in the human body. They bind to molecules and alter them in specific ways. They are essential for respiration, digesting food, muscle and nerve function, among thousands of other roles. In this article, we will explain what an enzyme is, how it works, and give some common examples of enzymes in the human body. Enzymes are built of proteins folded into complicated shapes; they are present throughout the body. The chemical reactions that keep us alive — our metabolism — rely on the work that enzymes carry out. Enzymes speed up catalyze chemical reactions; in some cases, enzymes can make a chemical reaction millions of times faster than it would have been without it.

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Soil Sci. Plant Nutr. Rao, R.

List of enzymes

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Enzymes: How they work and what they do

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Donatien C. 22.03.2021 at 15:25

An enzyme is a type of protein found within a cell.

Lewis A. 28.03.2021 at 06:42

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