 Hey everybody, Dr. O here. Let's talk about enzymes. Now first, you have to be in awe of these things. You have to understand that life would absolutely not be possible without enzymes. Let's go ahead and take a look at why. So first, there's a couple of things. Most enzymes are made of protein. So there are ribosomes and there are enzymes that are made of other things. But the huge majority of enzymes are made of protein. That's the first in the note. Secondly, usually you can tell an enzyme by its name, it will end in ACE, ASC, so an ACE ending. It's just a couple of quick things here. But then how do they work? So maybe you've heard this, but enzymes work by lowering activation energy. As you can see here on the left and right hand sides, both these images are showing different amounts of energy being needed to turn reactants into products. So without an enzyme, you would have a high activation energy and it would take too much energy in most situations. With an enzyme, you're going to see a lower activation energy. So this, I don't like these pictures though, just because they make it look like, okay, an enzyme makes something work a little bit better, right? But a real picture would be, take the picture on the right hand side, that's what an enzyme would look like, or a reaction would look like with an enzyme with a low activation energy. On the other side, this should be to the roof at least. The difference between having an enzyme and not is just unbelievable. So let me give you a number here to keep in mind. Enzymes can speed up chemical reactions, can make chemical reactions occur up to a billion times faster. So we're not talking about a 25 or 50% improvement. We're talking about with an enzyme, we're alive and have a metabolism. Without it, we couldn't do that. We don't have a century to wait for a reaction to occur. It has to happen now. So that's the first key number to remember, that enzymes can speed up chemical reactions up to a billion times faster. All right, the other key thing to note about enzymes is they're called biological catalysts. So a catalyst is something that can speed up a chemical reaction. But the key here with a biological catalyst is not only does it speed up a chemical reaction we just set up to a billion times faster, but it doesn't change the product and it's not used up in the reaction. So think about that. If we had an enzyme that turned this reaction into a product but broke it along the way, that wouldn't do us any good. Or imagine if we spent the energy to build an enzyme and that enzyme was broken as it produced this product, it would be a complete waste. So the same enzyme can work over and over and over again. The turnover rates of some enzymes are 20,000 times a second. So one enzyme can perform up to 20,000 reactions in a second. And it can do that for days or weeks until it has to be replaced. So that's why it's important that it's a catalyst, that it speeds up the reaction but doesn't change the reaction or itself. But the other important thing here is that they're biological catalysts. And when I say that, what I think of is it's easy to speed up chemical reactions. I can increase temperature. I can add acids in a laboratory right. I can speed up chemical reactions. But these biological catalysts allow us to speed up chemical reactions without altering homeostasis. If we're going to go for a run, you can't crank your core temperature up to 140 degrees. You're dead. Or you don't want to drink hydrochloric acid or something before you work out. We can't use acid. We can't use temperature in the same way to speed up chemical reactions, at least not to any great degree. So we have these biological catalysts, these protein-based enzymes that speed up chemical reactions without altering our homeostasis, without damaging us in the process. So I think that's very, very important. All right. So the key things we've noted here is enzymes are protein. They have the ACE ending. They work by lowering activation energy. That's the most common thing you're going to hear. They have turnover rates of up to 20,000 reactions per second. That's unbelievable. Think about one Mississippi. There's a hydrolytic enzyme somewhere that just performed 20,000 reactions. They speed up chemical reactions up to a billion times faster. And then a biological catalyst allows us to do all this without destroying us in the process, without damaging homeostasis. All right. Other key things to note here, they are usually very specific. When you think of enzymes, think of locks and keys, the key that I use to get into my car is only going to start my car. So like the enzyme sucrose, for example, it's going to break down sucrose, but it won't break down lactose. The enzyme lactase will do that. So they're specific. That's a key thing. A few more things here, a lot to know about enzymes, but what are the kind of things that are going to influence how enzymes work? So here I just have a different picture here of an actual, of an enzyme working. What they do is they take this chaotic world and they organize and control it, and that's how they lower activation energy. They make these random processes more likely to occur. But the key things that will influence if this enzyme sitting here will actually do its job is going to be pH, substrate, concentration, and temperature. So enzymes are proteins and just like other proteins, if you change the pH too much or change the temperature too much, they will denature, they will fall apart. So that's why all enzymes have a pH range where they can work and a temperature range where they can work. This is why I think about a fever. If you get a really high fever for too long or your patients get really high fevers for too long, that can lead to organ failure. What's really happening is their enzymes are starting to denature and their enzymes aren't working. And without an enzyme, you don't have a metabolism. And without a metabolism, you don't have life. So that's really the cause of death because of a high fever or a condition where someone's pH drops too low is going to be their enzymes are unraveling. Substrate concentration, that just means that the more substrate there is around, the faster enzymes will work until they reach a saturation point where no matter how much more substrate that shows up, they're working as fast as they can. I can't do anymore. So there's a few more interesting things to note there. What else but enzymes? I have one more thing I wanted to show you. This is just another picture of the same thing. Now instead, let me go back here. This is an enzyme that's going to be breaking something apart. As you see, the substrate is larger and it's broken down to smaller products. Here's an enzyme that takes smaller reactants and builds a product. This would be a synthetic enzyme, but still has the same specificity. Everything else is the same. But the last thing I wanted to note is that many enzymes cannot work on their own. They need a cofactor or a coenzyme. In this situation, the protein portion is called an apoenzyme. Once you've added the cofactor or coenzyme, it's now a holoenzyme. I don't use those terms much, but I think it's very important to know what these cofactors or coenzymes are. Cofactors are going to be inorganic. These are primarily going to be minerals. So you think, why do I have to eat vitamins and minerals? Minerals are going to be the cofactors that power these enzymes. A good example is you need zinc for the enzyme DNA polymerase to work. If you're going to build new DNA, you need zinc. And then coenzymes are going to be vitamins. Almost all of them are going to be your vitamins. You need niacin to make NAD, riboflavin to make FADH2. These are going to be electron carriers, but they're going to be these enzymes. So that's what a cofactor and a coenzyme are. They basically activate or turn enzymes on. Cofactors being minerals, coenzymes being vitamins. OK, that's a lot, but I think that's everything you need to know to have a foundational understanding of enzymes and just understand that life would not be possible without them. So make sure you thank your enzymes. Have a wonderful day. Be blessed.