Captions are on! Click CC at bottom right to turn off. Follow us on Twitter (@AmoebaSisters) and Facebook! Is it odd to have a favorite protein? Well…I don’t think so. Probably because my favorite protein happens
to remind me of one of my favorite childhood games: Pac-Man. If you haven’t played Pac-Man before, then
chances are…we are much, much older than you. But now you can play it on Google- just Google
Pac-Man—it’s a Google Doodle! Anyway, I digress. See, in Pac-Man, you have this little character. It goes around, finds these pebbles, and the
pebbles fit right into it. Well, a lot of illustrations that you will
find of enzymes happen to look, to us, a lot like Pac-Man. I remember P for Pac-Man and P for protein. Most enzymes are proteins. In the game we mentioned, these little pebbles
that Pac-Man goes after.

Well, enzymes have a specifically shaped area, called an active site, where items can bind, called substrates. It’s very specific binding because the active site is specifically shaped for the substrate that binds there. Very specific. So what happens when substrates bind to an enzyme? Well, usually the substrate is held there with weak bonds because it’s not going to stay there forever. Something called induced fit will happen, which means the active site can change its shape even more to bind that substrate perfectly. Like…an enzyme-substrate hug. The enzyme can either build up or break down the substrates that specifically bind to it, and we call the resulting item the product. An enzyme has the ability to really speed up reactions. Reactions that technically could happen on their own …but with the help of enzymes, they can be sped up to make processes effective for life. Let me give you a great real-life example. The enzyme lactase. Another really cool thing about enzymes is that they often end in -ase like lactase.

Many sugars, on the other hand, end in -ose,
and lactose is an example of a sugar. Lactose is a disaccharide, meaning it contains
two sugar molecules bound together. We don’t actually digest it so well in that
form. It’s big. The enzyme lactase has the ability to break
lactose into smaller parts that our body can digest, and this is a lot better option than
waiting for a chemical reaction with lactose to happen spontaneously. With lactase enzyme, lactose can be broken
down quickly and digested. Now there are some people that do not produce
enough lactase enzymes. They can be what we call lactose intolerant,
which means that consuming foods that have lactose, milk sugar, in them can make them
sick. They can’t break the lactose down efficiently
without lactase enzymes. Now in that example, one thing to point out---lactase,
the enzyme, can break down a lot of lactose,

the substrate. The lactase doesn’t get used up in the reaction. It’s still there. We call enzymes a catalyst because they can
be used over and over in the reaction. By the way, your digestive system uses all
kinds of enzymes. You have lipase that breaks down lipids- which
are fats. You have amylase which breaks down starch. You have protease which breaks down proteins. So as you can see, the digestive system is
very involved with enzymes. Another thing to point out is that enzymes
don’t always work alone. Sometimes they get some help. Some often underappreciated but essential
little helpers are called cofactors and coenzymes. They may bind to the substrate or to the active
site. They help the enzyme do its job of building
up or breaking down substrates into products. Now you didn’t forget our Pac-Man analogy
yet, right? In the game Pac-Man, there are these ghosts.

And when they touch Pac-Man, it makes this sound…it’s like…ner ner ner ner. The Pac-Man’s shape gets all distorted in the process. So what does this have to do with enzymes? No, there aren’t ghosts around. But enzymes do have certain ideal conditions that they like. For example, an enzyme that is in your stomach would have an ideal pH that is very acidic because the environment in your stomach is very acidic. Different enzymes have different ideal pH and temperature ranges. If an environment changes out of an enzyme’s ideal pH or temperature range, then something that reminds me a lot of that horrible sound I tried to make can happen. The enzyme becomes…denatured! That means its shape becomes distorted- it can no longer bind to its substrate. It can no longer work correctly. It is…finished. Well….that’s a dramatic end to enzymes. Keep in mind that if you have an interest in this topic, many medical researchers have

a large focus on enzymes. Enzymes regulate a lot of body processes,
and many diseases can involve specific enzyme production…or the lack of it. Well, that’s it for the Amoeba Sisters, and
we remind you to stay curious!

Enzymes (Updated)

Enzymes (Updated)