Topic 3.6 Enzymes

Define enzyme and active site 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 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 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

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Lactase Lactase is used to remove the sugar lactose

from milk and other dairy products

Lactose intolerance 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

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ReactionSubstrate: Lactose

Lactose + H2O-galactosidase

Glucose + Galactose

This is a hydrolysis reaction

Advantages 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

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