Abstract
The distribution of net electric charge of amino acid sequences from Drosophila melanogaster is compared with a Gaussian distribution to investigate the balance between randomness and selection in the process of evolution. The net electric charge follows a Gaussian-like distribution, with a slight but systematic deviation from the Gaussian distribution. This deviation is not observed for eleven subsets of proteins of similar size, and it is shown that the mean and variance of the Gaussian distribution appear to be linearly dependent on the size of proteins. The Gaussian distribution is centered around a charge density of approximately one positive charge per 100 residues, which in comparison to the real distribution for random sequences, reveals some degree of charge correlation in the proteome of D. melanogaster. These findings suggest the possible involvement of a systematic selection mechanism in the evolution process.
