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Title: Enzymes
Description: Biology notes for enzymes including characteristics, factors and classification of enzymes, as well as commercial applications of enzymes
Description: Biology notes for enzymes including characteristics, factors and classification of enzymes, as well as commercial applications of enzymes
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Enzymes Notes
Enzymes are
proteins
(biomolecules)
that function as biological catalysts (
increase the rates
of chemical
reactions
but not yield without being changed by the reaction)
...
They build and break down proteins and tissues, remove toxins and turn
nutrients into energy etc
...
g
...
These are digested by digestive enzymes, e
...
amylase, maltase, protease
and lipase
...
The reactions can be either anabolic or catabolic
...
E
...
amino
acids taken into the cell may be used to build up proteins
...
Catabolic reactions (Exothermic) are the breakdown of more complex organic
molecules into simpler substances, where energy is usually released
...
g
...
Almost all chemical reactions in a
biological cell
need enzymes
in order to occur at rates sufficient for life
...
The substrate binds with the enzyme, forming an enzymesubstrate
complex
...
The specificity of an enzyme is due to the 3dimensional shape and thus, the enzyme is
complementary one substrate only (lock and key hypothesis, where only one key can fit one lock)
...
Enzymes work by lowering
the
activation energy
for a reaction, thus dramatically increasing the rate of the reaction
...
Most enzyme reaction rates are millions of times faster
than those of comparable uncatalysed reactions
...
Enzymes are known to catalyse about 4,000 biochemical reactions
...
Enzymes are commonly named by using the suffix “ase” to the end of the enzyme’s name
...
g
...
ase
ase
Enzymes’ Characteristics
●
Enzymes are proteins that speed up (catalyse) biochemical reactions
...
The same
enzyme molecule can process a large number of substrate molecules
...
●
Enzymes and substrate must bind to form an enzymesubstrate complex
...
E
...
cyanide, mercury, lead, arsenic and
carbon monoxide
...
Often
competitive inhibitors strongly resemble the real substrate of the enzyme
...
In uncompetitive inhibition, the inhibitor cannot bind to the free enzyme, only to the
substrate
...
This type of inhibition is rare, but may
occur in multimeric enzymes
...
These changes the enzyme shape and the substrate cannot bind to
the enzyme
...
Factors Affecting Enzyme Activity
When the threedimensional structure of an enzyme is altered beyond functional parameters and the
active site is no longer complimentary to its specific substrate, the enzyme is said to be denatured
...
Many
factors can affect the activity of an enzyme e
...
drugs, pressure, temperature, pH, enzyme concentration
and substrate concentration
...
Temperature affects enzyme speed and the enzyme
...
The wrong temperature will cause a cell to stop growing, even death
...
Above optimal temperature will result in the rate of reaction
decreasing sharply
...
The active site of the enzyme loses its original shape and the substrate can now no longer fit
into the active site
...
With every 10 degree Celsius, the rate of enzyme activity doubles
...
Enzymes are highly sensitive to pH
changes
...
g
...
g
...
At pH values higher or lower than the optimal level, ionic
bonds within the enzyme can be disrupted and this changes the active site
...
●
Substrate Concentration The rate of an enzymecatalysed reaction increases in direct
proportion to the substrate concentration until a maximum value when the enzyme molecules
are all saturated (substrate molecules have occupied all active sites of the enzyme molecules at
any given time)
...
g
...
g
...
The functional
groups in proteins are limited to those of the amino acid side chains
...
E
...
Trace minerals and
certain vitamins are a dietary necessity because they function as building blocks for cofactors and we
cannot synthesize them
...
These enzymes require coenzymes
that are reduced or oxidized as the substrate is oxidized or reduced
...
The digestion of
c
carbohydrates and proteins by hydrolysis requires these enzymes (carbohydrases & proteases)
...
Such reactions are generally not
c
favorable and require energy from ATP hydrolysis
...
Kinases transfer a
phosphate group from ATP to give ADP and a phosphorylated product
...
●
Beer Proteases are added to beer to catalyse the breakdown of proteins that causes the beer
to look hazy when chilled
...
●
Meat Tenderization Meat is a muscle that contains a lot of proteins
...
●
Medical Applications Enzymes are used to monitor blood glucose levels, drugs and hormones
...
●
Icecream Lactase catalyses the hydrolysis of lactose in making icecream
...
●
Textiles Amylase helps remove starch that is used as stiffeners from fabrics
...
Detergents Protease and amylase help dissolve protein and starch stains in clothes
Title: Enzymes
Description: Biology notes for enzymes including characteristics, factors and classification of enzymes, as well as commercial applications of enzymes
Description: Biology notes for enzymes including characteristics, factors and classification of enzymes, as well as commercial applications of enzymes