Enzymes Lab

Enzymes Lab
I. Introduction
A. Enzyme definition
1. Protein – composed of amino acids
2. Catalytic- increase rate of a reaction
B. Mechanism of action
1. Based on shape
2. E + S ES complex  E + P
3. “Lock and Key”
4. Very specific
5. Decrease in energy of activation
II. Experimental design
A. Background
1. Beano contains an enzyme that breaks down indigestible fiber
(cellulose) into digestible monomeric units (glucose). This fiber is found
in high quantities in foods like beans and chick peas. When the fiber is not
digested in the small intestines, it is passed into the large intestines. It is
then fermented by bacteria in the large intestine producing gas. This
causes the well known, socially embarrassing side effect associated with
the consumption of these food sources.
2. Available reagents
a. Chick peas
b. Liquid Beano
c. Benedicts reagent
d. glucose solution
B. Assignment- Design an experiment to demonstrate the action of Beano on the
macromolecules contained within chick peas. You will be limited to the use of the
reagents present within the lab. Be sure to incorporate the use of positive and
negative controls in experimental design.
1. Review the theory behind Benedicts reagent reaction
2. Review procedures for the benedicts test.
Benedicts test for reducing sugar
a. The Cu+2 ion contained within the reagent is reduced to Cu+ by
reacting with the free aldehyde or ketone group present in all
monosaccharides and some disaccharides.
b. Mix approximately equal volumes of solution to be tested with
the Benedicts reagent. Heat in boiling water bath for 5 minutes.
c. Positive test is noted for color changes to green, orange, brick
red or brown.
d. Negative results are seen as blue (No color change)
3. Work in groups of 4 students
4. Instructors may help improve the experimental design.
C. Hints
Cellulose is a polymer of glucose
Glucose will be released by the catalytic action of the enzyme in
Beano on the cellulose
The release of this glucose can be monitored by observing the reaction
with Benedicts reagent
Enzyme action requires several minutes to occur at room temperature
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