A NEW METHOD OF CALCULATING EVOLUTIONARY RATES OF PROTEINS APPLIED TO INSULIN AND C‐PEPTIDES

The optimal number of differences between sequences for phylogenetic studies is derived, and the developed theory is used to show that a sequenced peptide assumed to be duck proinsulin C-peptide had the expected differences from the mammalian C-peptides. The theory is used to separate the guinea pig insulin from other insulins, indicating that the pressure of selection on guinea pig insulin has been significantly lower than that on other insulins. Finally, calculation of the half-life of a protein as a measure of the pressure of selection rather than the evolutionary rate constant is proposed.