Iodine Test (Color and Enzyme Activity Level) a). Describe the effect of enzyme

Question

Iodine Test (Color and Enzyme Activity Level)

a). Describe the effect of enzyme concentration observed on the hydrolysis reaction of startch.

Effect of Tempature (Temp of warm water for Sol 1: 37 C, Temp of boiling water for Sol 2: 89 C, Temp of ice bath for Sol 3: 4 C)

a). What is the optimum temperature for a-amylose?

b). Explain how temperature, pH, and an inhibitor affect enzyme activity.

Time Solution #1 Solution #2 Solution #3 Solution #4 0 min Blue-Black 0 Blue 1 Blue 1 Gold 3 5 min Blue-Black 0 Gold 3 Gold 3 Gold 3 10 min Blue-Black 0 Gold 3 Gold 3 Gold 3

Explanation / Answer

a)The enzyme has to bind to the substrate, giving an enzyme substrate complex. Here the presence or absence of starch in solution is recognised using iodine.Starch is hydrolysed by the enzyme amylase, to form glucose units. Iodine forms a complex with starch, but not with glucose.If glucose is present,it forms gold color. If starch is present, it forms blue color.

Solution 1 shows blue-black color,meaning the starch is not hydrolysed and enzyme is not active

Solution 2 shows first blue color and then gold, meaning enzyme is low initially and then gets active after 5 min.

Solution 3 shows the same.

Solution 4 shows the activity of the enzyme from beginning and has high activity.

All enzymes have an optimum temperature which corresponds to maximum activity.The tubes with the enzyme and substrate are placed in hot water bath at 370 and 890 c and in a cold water bath for 10 min.Then iodine solution is added to see the enzyme activity. Here in the experiment, solution 1 and 3 shows gold color, meaning enzyme activity is high .Solution 2 shows blue -black color, where there is no enzyme activity.

b) Warm water is ideal for enzyme activity i.e, at 370 c.

c)All reactions are faster at higher temperature.The enzymatic reactions become slow or completely stop if the temperature is too high,as enzymes are denatured.Optimum temperature corresponds to high activity. Same way, optimum pH corresponds to maximum activity of the enzyme.Most of the enzymes show good activity at pH around 7.Some enzymes work well in acidic pH. Inhibitors are substances that stop or slow down the enzymes. Some are competitive and non-competitive .They bind to the enzyme and prevent them from binding to the substrate.

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