1. Topic 3.6 Enzymes

2. 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

3. EXPLAIN the effects of temperature, pH and substrate concentration on enzyme activity

4. 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

5. 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

6. Enzyme-Substrate Specificity

8. Enzymes have been used in biotechnology for millennia http://www.touregypt.net/featurestories/bread.htm

9. Lactase  Lactase is used to remove the sugar lactose from milk and other dairy products

10. 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

11. Source Lactase enzyme (  -galactosidase) is extracted from fungi such as Aspergillus oryzae http://www.biologie.uni-regensburg.de/ http://biotech.nikkeibp.co.jp/MUSEUM/3.html

12. Reaction Substrate: Lactose Lactose + H 2 O  -galactosidase Glucose + Galactose This is a hydrolysis reaction

13. 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 Stoney Creek Dairy