In this video, we'll take a look at the 5th class of enzymes, our lyases. Now here they catalyze the addition or removal of functional groups without hydrolysis or redox reactions. Here, the addition and removal of groups help to break and create double bonds respectively. With this type of enzyme class, we have subclasses. Our subclasses include dehydrogenases, which help to remove water; hydrotases help to add water. We have deaminases, which help to remove amino groups, so NH3. And then decarboxylases, this isn't as easy to see, but decarboxylation deals with the removal of CO2. If we take a look at our two reactions, we start out with fumarate here, and we're going to use fumerase or hydrotase, which means we're going to add water. We're adding water to this pi bond. So here, in order to add to those 2 carbons, we have to destroy the pi bond, remove it, and here's the water we added, in the form of OH and H.
Below that, we have Tyrosine. And with this Tyrosine, we're using Tyrosine decarboxylase. Remember, decarboxylation means a loss of CO2. The CO2 that we're going to lose is this one here. We lose that CO2. So now that carbon here has lost that CO2. It's gained a hydrogen to remake the loss because remember, carbon must make 4 bonds. And here goes the CO2 that was lost. So again, remember, here we're dealing with lyases and there are quite a few subclasses when it comes to this particular class of enzymes. So, keep that in mind to properly identify what exactly we are adding or removing to properly identify the subclass of enzyme.
