Enzymes Many
chemical transformation processes used in various industries have inherent drawbacks
from a commercial and environmental point of view. Non-specific reactions may
result in poor product yields. High temperatures and/or high pressures needed
to drive reactions lead to high energy costs and may require large volumes of
cooling water downstream. Harsh and hazardous processes involving high temperatures,
pressures, acidity or alkalinity need high capital investment, and specially designed
equipment and control systems. Unwanted by-products may prove difficult or costly
to dispose off. High chemical and energy consumption as well as harmful by-products
have a negative impact on the environment. All
of these drawbacks can be virtually eliminated by using ENZYMES.
Enzyme reactions are carried out under mild conditions, they are highly specific,
involve very fast reaction rates, and are carried out by numerous enzymes with
different roles. Industrial enzymes originate from biological systems; they contribute
to sustainable development through being isolated from microorganisms which are
fermented using primarily renewable resources. In
addition, as only small amount of enzymes are required to carry out chemical reactions
even on an industrial scale, both solid and liquid enzyme preparations take up
very little storage space. Mild operating conditions enable uncomplicated and
widely available equipment to be used, and enzyme reactions are easily controlled
and can be stopped when the desired degree of substrate conversion has been achieved.
Enzymes also reduce the impact of manufacturing on the environment by reducing
the consumption of chemicals and energy, and the subsequent generation of waste. Developments
in genetic and protein engineering have led to improvements in the stability,
economy, specificity and overall application potential of industrial enzymes.
When all the benefits of using enzymes are taken into consideration, it's not
surprising that the number of commercial applications for enzymes is increasing
every year. Class
of Enzyme Reaction Profile
- Oxidoreductases:
Oxidation reactions involve the movement of electrons from one molecule to another.
In biological systems we usually see the removal of hydrogen from the substrate.
Typical enzymes in this class are called dehydrogenases.
- Transferases:
This class of enzymes catalyses the transfer of groups of atoms (radicals) from
one molecule to another. Aminotransferases or transaminases promote the transfer
of an amino group from one amino acid to an alpha-keto-acid.
- Hydrolases:
Hydrolases catalyse reactions between a substrate and water, and bind water to
certain molecules. In this way, larger molecules are broken up into smaller units.
This class of enzymes catalyses the cleavage of peptide bonds in proteins, glucosidic
bonds in carbohydrates, and ester bonds in lipids.
- Lyases:
Lyases catalyse the addition of groups to double bonds or the formation of double
bonds through the removal of groups. Thus bonds are cleaved using a different
principle to hydrolysis. Pectate lyases, for example, split the glycosidic linkages
by beta-elimination.
- Isomerases:
Isomerases catalyse the transfer of groups from one position to another on the
same molecule. In other words, these enzymes change the structure of a substrate
by rearranging its atoms.
- Ligases:
Ligases join molecules together with covalent bonds. These enzymes participate
in biosynthetic reactions where new groups of bonds are formed. Such reactions
require the input of energy in the form of cofactors such as ATP.
The
Nature of Enzymes Enzymes are biological catalysts in the form of
globular proteins that drive chemical reactions in the cells of living organisms.
As such, they have evolved - along with cells - under the conditions found on
planet Earth to satisfy the metabolic demands of an extensive range of cell types.
In general, these metabolic demands can be defined as: - Chemical
reactions take place under mild conditions
As the cells of nearly
all animals, plants, and microorganisms can only function optimally within a fairly
narrow temperature range, enzymes carry out chemical transformations under very
mild conditions.
In
order for this reaction to proceed non-enzymatically, heat has to be added to
the maltose solution to increase the internal energy of the maltose and water
molecules, thereby speeding up their collision rates and the likelihood of their
reacting together. The heat is supplied to overcome a barrier called 'activation
energy' so that the chemical reaction can be initiated. As an alternative, the
enzyme maltase can drive the same reaction at 25°C by lowering the activation
energy barrier. It does this by capturing the chemical reactants - called substrates
- and bringing them into intimate contact at 'active sites' where they interact
to form one or more products. As the enzyme itself remains unchanged by the reaction,
it continues to catalyse further reactions until an appropriate constraint is
placed upon it. - Specific
action according to enzyme class
To avoid metabolic chaos and create
harmony in a cell teeming with innumerable different chemical reactions, the activity
of a particular enzyme must be highly specific, both in the reaction catalysed
and the substrates it binds. Some enzymes may bind substrates that differ only
slightly, whereas others are completely specific to just one particular substrate.
An enzyme usually catalyses only one specific chemical reaction or a number of
closely related reactions. Unlike non-enzymatic chemical reactions, enzyme reactions
rarely lead to the formation of waste by-products. - Very
fast reaction rates
The cells and tissues of living organisms have
to respond quickly to the demands put on them. Such activities as growth, maintenance
and repair, and extracting energy from food have to be carried out efficiently
and continuously. Again, enzymes rise to the challenge. Enzymes accelerate reactions
by factors of at least a million. Carbonic anhydrase, which catalyses the hydration
of carbon dioxide to speed up its transfer in aqueous environments like the blood,
is one of the fastest enzymes known. Each molecule of the enzyme can hydrate 100,000
molecules of carbon dioxide per second. This is equivalent to ten million times
faster than a non-enzyme-catalysed reaction. - Numerous
enzymes for different tasks
Because enzymes are highly specific
in the reactions they catalyse, an abundant supply of enzymes must be present
in cells to carry out all the different chemical transformations required. Most
enzymes help break down large molecules into smaller ones and release energy from
their substrates. To date, scientists have identified over ten thousand different
enzymes. Because there are so many, a logical method of nomenclature has been
developed to ensure that each one can be clearly defined and identified.
Although
enzymes are usually identified using short trivial names, they also have longer
systematic names. Furthermore, each type of enzyme has a four-part classification
number (EC number) based on the standard enzyme nomenclature system maintained
by the International Union of Biochemistry and Molecular Biology (IUBMB) and the
International Union of Pure and Applied Chemistry (IUPAC). Most enzymes catalyse
the transfer of electrons, atoms or functional groups. And depending on the types
of reaction catalysed, they are divided into six main classes, which in turn are
split into groups and subclasses. For example, the enzyme that catalyses the conversion
of milk sugar (lactose) to galactose and glucose has the trivial name lactase,
the systematic name beta-D-galactoside galactohydrolase, and the classification
number EC 3.2.1.23.
Industrial
enzymes are produced using a process called Submerged Fermentation. This involves
growing carefully selected microorganisms (bacteria and fungi) in closed vessels
containing a rich broth of nutrients (the fermentation medium) and a high concentration
of oxygen (aerobic conditions). As the microorganisms break down the nutrients,
they release the desired enzymes into solution. Thanks to the development of large-scale
fermentation technologies, today the production of microbial enzymes accounts
for a significant proportion of the biotechnology industry's total output. Fermentation
takes place in large vessels called fermenters with volumes of up to 1,000 cubic
meters. The fermentation "Media" comprise of sterilized nutrients based
on renewable raw materials like maize starch, sugars and soya grits. Various elementary
salts are also added depending on the microbe being grown. Most industrial enzymes
are secreted by microorganisms into the fermentation medium in order to break
down the carbon and nitrogen sources.
Both
batch-fed and continuous fermentation processes are common. In the batch-fed process,
sterilized nutrients are added to the fermenter during the growth of the biomass.
In the continuous process, sterilized liquid nutrients are fed into the fermenter
at the same flow rate as the fermentation broth leaving the system, thereby achieving
steady-state production. Operational parameters like temperature, pH, feed rate,
oxygen consumption and carbon dioxide formation are usually measured and carefully
controlled to optimize the fermentation process.
Enzymes In Paper
The enzymes offered for the Paper Industry is for new process to modify cellulose fibers in order to optimize the bleaching, refining, de-inking of paper . These products have been specifically formulated to work on different types of Paper The different types of Products offered to the Industry are Sebrite DI( Enzymes for Deinking), Sebrite Bleach ( Enzymes for pre-bleaching) Some of the benefits that have been seen include improved brightness, improved strength characteristics, cleaner white water systems, less linting and dusting, reduction in stickies and environmental benefits like wastewater stream cleaning and reduction in total Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD).
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