Previous studies have established the factors, including solvent accessibility of protein, that determine the protein evolutionary rate. However, in human, this accessibility’s relationship to protein evolutionary rate remains unclear due to discrepancy of previous studies' results. Following the study done by Lin et al. (2007) which involved Saccharomyces cerevisiae as the model organism, in the recent work, we study Homo sapiens as the model organism to find out the influence of solvent accessible residues on the rate of protein evolution. The present study's result suggested that solvent accessibility of residues in human protein significantly yet weakly correlates with synonymous substitution rates, and there is some correlation change when the dataset was divided into six groups, confirming the account of alignment length in the correlation. Moreover, this study establishes that synonymous substitution rates of human protein are stable whatever the alignment lengths are.
