Variability patterns of dehydrogenases versus peptide hormones and proteases/antiproteases

Comparisons of human/rat species variants of 23 dehydrogenases versus 41 entries for peptide hormones and 41 for proteases/antiproteases reveal characteristic patterns. Dehydrogenases are 'constant' (2-8% residue differences between homologues) or 'variable' (12-40% differences). Peptide hormones exhibit a wider range, with many 'strictly conserved' and others spreading upscale, while proteases/antiproteases are overall shifted upscale, with few 'constant' and many 'variable'. Overall, the influence of polypeptide size and function is confirmed, while for the dehydrogenases, the data highlight the 'constant' pattern as the one with high frequency values and suggest for classic liver alcohol dehydrogenase the 'variable' pattern to correlate with emerging functions.