Enzyme Technology
Why enzymes?
Catalysts increase the rate of
otherwise slow or imperceptible reactions without undergoing any net change in
their structure. The early development of the concept of catalysis in the
19th century went hand in hand with the discovery of powerful
catalysts from biological sources. These were called enzymes and were later
found to be proteins. They mediate all synthetic and degradative reactions
carried out by living organisms. They are very efficient catalysts, often far
superior to conventional chemical catalysts, for which reason they are being
employed increasingly in today's high-technological society, as a highly
significant part of biotechnological expansion. Their utilization has created a
billion dollar business including a wide diversity of industrial processes,
consumer products, and the burgeoning field of biosensors. Further applications
are being discovered continually.
Enzymes have a number of distinct advantages
over conventional chemical catalysts. Foremost amongst these are their
specificity and selectivity not only for particular reactions but also in their
discrimination between similar parts of molecules
(regiospecificity) or optical isomers
(stereospecificity). They catalyse only the reactions of very
narrow ranges of reactants (substrates), which may consist of a
small number of closely related classes of compounds (e.g., trypsin catalyzes the
hydrolysis of some peptides and esters in addition to most proteins), a single
class of compounds (e.g., hexokinase catalyzes the transfer of a phosphate group
from ATP to several hexoses), or a single compound (e.g., glucose oxidase oxidises
only glucose amongst the naturally occurring sugars). This means that the chosen
reaction can be catalysed to the exclusion of side-reactions, eliminating
undesirable by-products. Thus, higher productivities may be achieved, reducing
material costs. As a bonus, the product is generated in an uncontaminated state
so reducing purification costs and the downstream environmental burden. Often a
smaller number of steps may be required to produce the desired end-product. In
addition, certain stereospecific reactions (e.g., the conversion of glucose into
fructose) cannot be achieved by classical chemical methods without a large
expenditure of time and effort. Enzymes work under generally mild processing
conditions of temperature, pressure and pH. This decreases the energy
requirements, reduces the capital costs due to corrosion-resistant process
equipment and further reduces unwanted side-reactions. The high reaction
velocities and straightforward catalytic regulation achieved in enzyme-catalysed
reactions allow an increase in productivity with reduced manufacturing costs due
to wages and overheads.
There are some disadvantages in the use of enzymes which
cannot be ignored but which are currently being addressed and overcome. In
particular, the high cost of enzyme isolation and purification still discourages
their use, especially in areas which currently have an established alternative
procedure. The generally unstable nature of enzymes, when removed from their
natural environment, is also a major drawback to their more extensive
use.
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This page was established in 2004 and last updated by Martin
Chaplin on
6 August, 2014
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