Lactase activity

From: Karen Kalumuck (
Date: Tue Nov 17 1998 - 13:06:09 PST

        Hello! I am the originator of the Lactase enzyme activity. I'm
sorry that it's taken so long for me to respond, but it's been an
exceptionally hectic few weeks of late.

        If you want to use this activity for an exploration of enzyme
activity it can be easily adapted. Students could perform the activity in
test tubes, and put one on ice, one at room temp, one at body temperature
and one in a boiling waterbath. Add the lactase drops, wait a minute, and
test for glucose. There should be definite differences. They may want to
periodically check the one in the cold to see if their results change. (the
boiling water should denature the lactase, and no change will occur; cold
should drastically slow the enzyme activity). Alternately you may want
boil one of the bottles of lactase enzyme, thus destroying its activity by
denaturing the enzyme.

        Practical applications: optimal enzyme activity is closely tied to
temperature. Enzymes that function in our bodies function optimally at
body temperature, 37 degrees C. Another example: baking bread. Often,
when yeast is added to dough in preparation of bread, it is let "rise" in a
warm spot. The warmth provides the yeast an optimal environment for their
enzymes to rapidly function, digest the sugar in the bread and produce the
gas that causes the bread to "rise". If the bread were put in the
refrigerator, this process would occur very slowly, due to lowered enzyme
activity, if it would happen at all.

        Food is refrigerated to retard bacterial growth; much of that is
closely tied with their enzyme function. Enzymes are responsible for
creating cellular materials and allowing cells to divide --- if the
bacterial enzymes are slowed, as in refrigeration, they do not grow rapidly
and spoilage --- and potential food poisoning, is minimized.

        Hope this answers your question!

----Karen Kalumuck

Karen E. Kalumuck, Ph.D.
Exploratorium Teacher Institute
3601 Lyon St.
San Francisco, CA 94123

This archive was generated by hypermail 2.1.3 : Mon Apr 24 2006 - 11:34:46 PDT