Genes, Polypeptides and Enzymes  One Gene – One Polypeptide Hypothesis  Exceptions to this rule: some genes = tRNA or mRNA not polypeptides  DNA sequences as gene regulators..not translated into proteins

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 © 2008 Paul Billiet ODWSODWS

Enzymes have been used in biotechnology for millennia © 2008 Paul Billiet ODWSODWS

Lactase  Lactase is used to remove the sugar lactose from milk and other dairy products © 2008 Paul Billiet ODWSODWS

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 © 2008 Paul Billiet ODWSODWS

Source Lactase enzyme (  -galactosidase) is extracted from fungi such as Aspergillus oryzae © 2008 Paul Billiet ODWSODWS

Reaction Substrate: Lactose Lactose + H 2 O  -galactosidase Glucose + Galactose This is a hydrolysis reaction © 2008 Paul Billiet ODWSODWS

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 © 2008 Paul Billiet ODWSODWS