Enzymes act by stabilizing the intermediate, smoothing the path from start to finish. Then, the intermediate falls apart, releasing sulfur dioxide and forming the desired product, shown on the right. The two molecules on the left come together, forming an unstable intermediate shown at the center in red. For instance, look at the Diels-Alder reaction shown here at the bottom of the illustration.
![introduction to bioedit and swiss pdb viewer introduction to bioedit and swiss pdb viewer](https://www.eurekaselect.com/images/graphical-abstract/cp/17/1/005.jpg)
Enzymes work by easing molecules through a difficult chemical change. Researchers have used the incredible functional diversity of the immune system in a clever way: to design new enzymes. These lymphocytes may also make small adjustments on the antibodies they produce, tailoring their antibodies to bind more tightly and more specifically. When an antibody encounters a virus or bacterium, the appropriate lymphocytes will multiply, flooding the blood with the particular antibodies needed to battle the invader. Each lymphocyte creates a different type of antibody, based on how it has recombined its antibody genes. This amazingly huge collection of antibodies is created by recombination of genes in lymphocytes, the blood cells that make antibodies. There are so many different kinds of antibodies that one or two are bound to be the right ones to fight the infection. Instead, all of your antibodies are pre-fabricated, lying in wait until a virus or bacterium attacks.
![introduction to bioedit and swiss pdb viewer introduction to bioedit and swiss pdb viewer](https://dfzljdn9uc3pi.cloudfront.net/2021/12329/1/fig-3-full.png)
You don't make a special antibody when a virus or bacterium infects your body. Remarkably, all of these antibodies are created before they ever see a virus or bacterium. Each type binds to a different target molecule. Your blood contains upwards of 100,000,000 different types of antibodies.