Statistical analysis of protein molecules

In this paper, entropy and auto-correlation values of main chain dihedral angles of 22,356 protein molecules (with less than 90% sequence identity, and downloaded from the RCSB Protein Data Bank) are calculated and found to lie within a well specified range for most proteins. Also, the entropy values obey a Gaussian distribution, which indicates that entropy plays a crucial role in evolution and conservation of protein tertiary structures. A comparison of the auto-correlation values of the dihedral angles of the entire protein molecule with those of the alpha helices and beta sheets indicates that random coils play an important role in determining the tertiary structure of protein molecules.