Life Sciences lab classes explained

Here are some lovely results from today :)

So, following on from my previous post, what would happen if you added a sugar solution to your 3D array of red blood cells bound together by lectins?  Well, one of two things might happen.  Either,  the structure of the sugar in solution is so different from the sugar on the red blood cell surface to which the lectin is bound that nothing will happen......  Or,  if the structure of the sugar in solution is similar to the sugar to which the lectin has bound on the red blood cell surface, the sugar will compete for the binding site of the lectin proteins. In this case, the more complementary the sugar in solution is to the lectin, the lower the concentration the sugar will need to be to disrupt the binding of the lectins to the red blood cells. In any case, once the binding of the lectins to the red blood cells is disrupted, the 3D array will be lost. Simple really!

In practical 7 you will be mixing lectins with red blood cells. In this post I want to explain what is actually happening in this mixture... Red blood cells have sugars on their cell surface. These are either bound to proteins (glycoproteins) or lipids (glycolipids). Either way, the fact is that red blood cells have chains of sugars sticking out all over them. Lectins on the other hand are proteins that bind sugars. As I said in the previous post, there are many different lectin proteins, that bind different sugars. The important thing for the practical is that lectins bind more than one sugar at one time - i.e. lectins have more than one sugar binding site. So, what will happen if you mix red blood cells with lectin proteins? Take a look at the following diagram:   So, to put the above diagram into words: the lectins will bind the sugars on the red blood cells - but that's not all, one lectin might bind sugars sticking out of two different red blood ce...

You will be using a lectin protein in practical 7, so I thought you might want to know a little about lectins... Lectins are a group of proteins that bind sugars. Different lectin proteins are able to bind different sugars. For example, Jacalin is a lectin that binds the sugar galactose, and Ulex europaeus agglutinin is a lectin that binds fucose.  So how does a lectin bind a sugar? And, what makes the binding specific? Well, different sugars have different structures, for example, look at the following structures of galactose and fucose: You can see from these diagrams, that whilst galactose and fucose are both 6 membered ring structures, they have a different arrangement of OH groups and fucose has a  CH 3  group whereas galactose has a  CH 2 OH  group. Different lectins can recognise these differences because they have binding sites that are very specific to the structure of the sugar they target.  The binding site ...