Question

Why is it useful to compare protein structures in addition to protein sequences?

Short answer

It is useful to compare protein structure in addition to protein sequences because it reveals information about evolutionary relationships thatis not possible through sequences only.

Step-by-step solution

Conservation of structure

The structure of the proteins does not evolve as fast as the sequence of the same protein does.The evolution of the sequence of a protein may occur due to mutations. The structures do not evolve due to the ability to tolerate such mutation and to have a functional biological significance.

Comparing protein structure in addition to protein sequences

Evolution tends to conserve the protein structures more than their sequences. Comparing the structure of the proteins and their sequences reveal evolutionary relationships that are not apparent from the sequence only.