Comparison of distributions of intra-protein 4-tuples and inter-protein 4-tuples.

<p>From the left to right the 4-tuples are named from ‘A’ to ‘F’ respectively. The relative frequencies for intra-protein 4-tuples are relative to the total number of the occurrences of all types of 4-tuples in the protein interior. The relative frequencies for inter-protein 4-tuple are relative to the total number of the occurrences of all types of 4-tuples in the protein-protein interface.