So for instance, if a bacterial cell, if a bacteria infects our body, then one way to inhibit the activity of that bacterial cell is to inhibit in some way some type of enzyme by using transition state analogues. Now, another important application of transition state analogs is the following. We can actually create antibodies that have specific catalytic capabilities by using these transition state analogues. So we can now build antibodies with specific catalytic capabilities by using transition state analogues as antigens. And to demonstrate how this actually works, let's discuss the biosynthesis process, the biosynthesis of the heme groups. So remember, in proteins such as hemoglobin and myoglobin, we have these important prosthetic groups known as heme groups.