Download Topic 3.6 Enzymes

Topic 3.6 Enzymes
Define enzyme and active site
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Enzyme – protein catalysts that speed up the
rate of chemical reactions
Active Site - part of an enzyme where
substrates bind and undergo a chemical
reaction
EXPLAIN the effects of temperature, pH and
substrate concentration on enzyme activity
Define denaturation
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a process in which proteins or nucleic acids
lose the tertiary structure and secondary
structure which is present in their normal
state, by application of some external stress or
compound such as a strong acid or base, a
concentrated inorganic salt, or heat.
Loss of structure = loss of function
Introducing Enzymes
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They are catalysts so the make reactions easier
This increases productivity and yield
Globular proteins
As catalysts they are not consumed by the reaction
The may be used over and over again
Enzymes show specificity to the reaction they
control
Enzymes are sensitive to their environment so they
can be controlled by adjusting the temperature, the
pH or the substrate concentration
Enzyme-Substrate Specificity
Enzymes have been used in
biotechnology for millennia
http://www.touregypt.net/featurestories/bread.htm
Lactase
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Lactase is used to remove the sugar lactose
from milk and other dairy products
Lactose intolerance
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Some people are intolerant of lactose in milk they
cannot digest it
The lactose remains in the digestive system and is
fermented by bacteria
The result is nausea, cramps, bloating, gas, and
diarrhea occurring within 4h of consuming milk
products
The treatment includes taking a tablet of lactase
enzyme with a meal
The lactase digests the lactose in the food
A special lactose free diet may be necessary
Source
Lactase enzyme (-galactosidase) is extracted
from fungi such as Aspergillus oryzae
http://biotech.nikkeibp.co.jp/MUSEUM/3.html
http://www.biologie.uni-regensburg.de/
Reaction
Substrate: Lactose
-galactosidase
Lactose + H2O
This is a hydrolysis reaction
Glucose + Galactose
Advantages
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Lactose intolerant patients can
digest their food
Lactose free products can be
prepared for special diets
Lactase is used to hydrolyse
lactose in ice cream into glucose
and galactose to give it a sweeter
flavour
Stoney Creek Dairy