ABSTRACT

When you take a photo of your friend using a digital camera, you obtain a 2D projection image of a 3D object. Figure 39.1 shows a photo of wire art. From this projection image, it is rather hard to understand the overlapping structure. To obtain a complete 3D structure information, we have to take multiple photos from di erent directions as shown in Figure 39.2. Combining those photos, we may construct a 3D structure information, that is, a three-dimensional coordinate of all winding wires. Proteins are linear polymers built from 20 di erent l-α-amino acids, and thus we may consider them a sort of wire art. However, proteins are nanometers in size and much more complicated.