IB Biology Substrate Specificity of Digestive Enzymes Planning Investigation

There are two proposed mechanisms by which enzymes specificity can be put forward, 1) Lock and key model. where substrate act as key for enzyme as lock or in other words enzyme possess specific grooves where only specific substrate can be fixed 2) Induced fix model. where enzyme creates site for substrate when it comes in contact with it. In the given experiment we will investigate the substrate specificity of enzyme amylase towards its substrate Starch. We will also investigate the effect of various physical parameters like temperature, pH, enzyme concentration etc.
3. Hypothesis: Amylase has absolute specificity toward starch and will not act on any other polysaccharides. Similarly rate of conversion of starch to glucose is highly influenced by various factors like temperature, enzyme concentration and pH.
The tubes were arranged and 5ml of Starch, Cellulose and glycogen solution was added to them and incubated at 37C in water bath for 2-3min to allow the temperature of solution reach to 37C (water bath was switch on before experiment was started and was at set temperature).
Tubes were observed for red to brick red color indicating liberation of glucose. Appropriate blanks were kept to validate overall experimental procedure that includes Starch solution without amylase, tubes without starch or substrate etc. Development of red color indicates activity of Amylase and thus generation of glucose.
7. Control variables:
Temperature: Test tubes were arranged as mentioned earlier and 5ml of starch solution was added to them. Three different temperatures were used in this experiment. The water baths were set at 20C, 37C and 45C. When the substrate attained the temperature, 1ml of saliva was added to each tube and further incubated for 15min. After incubation few drops of benedict’s reagents were added to each and further incubated for 5 min. Color development was observed as above and noted.