Nonrandomness in Protein Sequences -- Evidence for a Physically Driven Stage
of Evolution
V.S. Pande, A.Y. Grosberg, T. Tanaka,
Proceedings of the National Academy of Sciences USA,
91(26), 12972--12975 (1994).
Abstract
The sequences, or primary structures, of existing biopolymers--in particular, proteins--are
believed to be a product of evolution. Are the sequences random? If not, what is the character of this
nonrandomness? To explore the statistics of protein sequences, we use the idea of mapping the sequence
onto the trajectory of a random walk, originally proposed by Peng et al. [Peng, C.-K., Buldyrev, S. V.,
Goldberger, A. L., Havlin, S., Sciortino, F., Simons, M. & Stanley, H. E. (1992) Nature (London) 356,
168-170] in their analysis of DNA sequences. Using three different mappings, corresponding to three basic
physical interactions between amino acids, we found pronounced deviations from pure randomness, and these
deviations seem directed toward minimization of the energy of the three-dimensional structure. We consider
this result as evidence for a physically driven stage of evolution.
