Safe Enzymology   Carl W. Vermeulen, PhD Science-Projects.Com Williamsburg, Virginia science_projects@yahoo.com

E n z y m o l o g y

| SUPPLIES NEEDED |

..... Today you will become acquainted with several common enzymes (amylase, catalase, lactase, and papaine) from very common sources. (Amylase and catalase are found throughout the biological world. Lactase and papaine are procured from the supermarket as Lactaid® and Meat Tenderizer, respectively. We will focus on the first three since they will show results within the course of 50 minutes. Key concepts: catalysis, enzymes, -ase, -ose, substrate-product, qualitative-quantitative, analogs, inhibition, competitive inhibition.

These four enzymes were chosen because they are observed by using four different strategies.

• With amylase, you will inspect one of the easiest to assay enzymes, one that degrades the macromolecule called amylose (aka: starch). The trick to dealing with amylase is knowing that stationery paper is coated with starch. If you apply amylase to a spot on the paper, allow it to sit for a few minutes, and then spray the paper with KI₃, you'll get a white spot on a dark background. In this workshop you will have squashed a variety of things onto the paper testing for amylase - from saliva, to leaves, to bark, to flower petals and even ground beef.
• With catalase, you will directly see the gaseous products fizz if catalase is present. The trick here is not in the method, but in finding which taxons do NOT possess it, and drawing conclusions about evolution and even about the timing of the development of the earth's atmosphere!
• With lactase, you will follow the course of reaction as it is manifested in the colorful degradation of a structural analog of its normal substrate, and using that "ONPG Test" as your tool, you will investigate a totally safe sort of enzyme inhibition subject that will provide wonderful biochemical and biological extensions onto your previous lessons on the lac-operon. This "feed-back" inhibition was originally elucidated in 2001 by a high schooler in London, who soon worked with five other students through Dr. V's website. To do: (must be done in this order: (1) add the merest speck of lactase (a la Lactaid®) to each tube. (2) At the various workstations, add a centimeter of each of the concentrated sugar solutions to their respective tubes (for "NS" [no sugar] add 1 cm of water), swirl tubes to mix; (3) at yet another workstation add 3 drops of ONPG to each tube, swirl to mix; (4) note the order in which the tubes turn yellow; (6) which ones were not inhibited?
• With papaine, only discussion will be given as the exercise takes several hours to work. The trick here is to add papaine to gelatin, both before and after it has gelled.