Either a Useful Learning Tool or a Complete Misapplication of Chemistry and a Waste of Candy

For a lot longer than I should admit (several years), the idea of comparing enzyme kinetics to people eating candy from a community candy dish has been floating around in my head. It all started when I was in graduate school and I noticed that the Jolly Ranchers that had been brought in after Halloween seemed to be eaten in a certain order. I thought that it would be amusing to chart this over time (but was too lazy and not quite nerdy enough to do so). The more I thought about this the more I liked this idea and the more I realized that it works pretty well as a model for how enzymes work^*.


The basic requirements for an enzyme catalyzed reaction are that you have:

Substrate: Basically this is your starting material. In our case, Jolly Ranchers.

Enzyme: This is a biological catalyst, which helps to convert the substrate to product while remaining unchanged. In this case, our enzymes are people^**.

Product: This is the end material. In this case we'll call it the empty candy wrappers.


You start off with a high concentration of substrate (candy) and a steady concentration of enzymes (people). On occasion, an enzyme and and substrate will collide (i.e. someone walks past the candy dish) and if the substrate is appropriate, a reaction may occur (the person unwraps and eats the candy). As time goes on, different substrates (flavors) collide with the enzymes and some are found to bind and be metabolized better than others. By graphing the amount of substrate used over time (or in this example, the amount of candy still remaining over time) it is possible to look at the rate of consumption and determine which is the preferred substrate.


When I have paid attention to this in the past, what I have found looks something like this.




You can see that clearly Cherry is eaten the fastest, with Watermelon, Apple and Lemon right behind. Grape is typically not consumed at the same rate and the preferred substrates are used first. Why no one bothers to eat the last Lemon is beyond me. I guess everyone is trying to be polite, but enzymes aren't usually concerned with manners.

Another thing that can be learned is that if one were to repeat this experiment with the new "Original Flavors" of Jolly Ranchers which substitute Blue Raspberry for Lemon, the resulting curves would likely look like this.





This graph indicates that Blue Raspberry is not only not the preferred substance but goes essentially untouched by the enzymes.

Much like actual enzymes, it is possible to obtain mutants which may show increased or decreased preference for various substrates. A mutant^*** which uses Blue Raspberry as the preferred substrate is highly desirable because...well, that means more of the others for the rest of us.

^* A highly simplified model with huge flaws, it should be noted.

^** Technically, our enzymes don't meet the requirements because they are changed when they become fat from all the candy, but surely you don't expect perfection from a silly model like this.

^*** A mutant which prefers Blue Raspberry is pretty much a freak. Good luck finding one to eat all the nasty Jolly Ranchers while leaving all the good ones for you.