Molecule, Protein s 11.6 Coenzymes & Inhibitors
Sometimes the protein needs a cofactor to be active or in order to catalyze chemical reactions. Okay, the cofactor can be a couple of different things that can either be an enzyme or skew me a metal ion or it can be a small organic molecule and if its a small, organic molecule, usually thats whats referred to as coenzyme small molecules that are needed For the enzyme to function, an easiest way to to to see why this is important is actually just a little bit of a cartoon. Drawing ok and so lets say we have a protein with an active site that looks like that so heres, my enzyme, all right and my substrate looks something like this. Alright, so it doesnt have the correct fit for lock and key model or even an induced fit. Okay, what happens is that you need the cofactor or coenzyme. Excuse me this is the substrate. You also need the presence of a cofactor to bind at the active site as well. When that happens, when you have the cofactor or coenzyme present at the active site, suddenly theres the right fit theres my cofactor and now my substrate can fit perfectly in that active site. Now that the coenzyme is present, if that coenzyme wasnt present in that particular area of the active site, this chemical reaction wouldnt have occurred and, of course, after this happens of the cofactor or coenzyme, and the enzyme are unchanged. But of course the substrate has been converted into products, so the enzyme and the cofactor can continue on to catalyze chemical reactions.
So this is required for these enzymes to work, the cofactor, whether it be a metal ion or a small molecule, which we call coenzymes in order for the substrate to be converted into products. So this is a required requirement for some enzymes. Additionally, there is some processes where a molecule can actually bind to the active site that isnt a cofactor or substrate, and that actually causes the enzyme to stop working or inhibits its function, and these are, of course, called inhibitors. These are molecules that cause enzymes to lose their function or their catalytic catalytic activity. Okay, all right and again Ill. Try to draw this to explain this. Okay, so lets say we have an enzyme with an active site that looks like this and lets say. The substrate is very straightforward, its also very same shape, so it could bind to their all right, and so, if everything is perfect, the enzyme will form a complex with the substrate and then of course, after some amount of time the substrate will be converted into products. So that, of course, is if everythings correct and, of course, as you remember, the very important a Soaker one variant prospect aspect of enzyme activity is the active site which responds to a specific shape of the substrate or will be an induced into a specific shape. Because of the substrates shape, so if anything disrupts this active site its shape, of course, the enzyme will no longer function.
How its supposed to okay, say, theres a molecule that can actually bind to the enzyme, but its not the perfect shape. Thats called an inhibitor, and so now that the inhibitor is bound to the active site of the enzyme. The substrate can no longer form a complex to be catalyzed, so there will be no products of this chemical reaction and, of course, that can be a very big problem for a lot of different biological activities. So the inhibitor molecules bind to the active site and basically change the shape so that the substrate no longer fits their into the active site. Additionally, you can have whats known as non competitive inhibitors. This is a competitive inhibitor because it binds directly to the active site. Additionally, you could have a scenario where draw our enzyme again, where something is you know, small, as a metal ion combined to one of not bind to the pro team, but not at the active site, and this induces a change in the overall shape of the enzyme.