Sequence sizes of eukaryotic enzymes

We have shown in earlier studies that an appreciable fraction of proteins display sequence size periodicity with periods of approximately 123 aa and approximately 152 aa for eukaryotes and prokaryotes, respectively. For any firm conclusions to be made, the issue of possible bias due to an overabundance of some protein families should be addressed in more than one way. Here we present the size distributions for various sequence ensembles of eukaryotic enzymes that differ by level of data bank cleaning. The sequences were purged by applying several successive thresholds of relatedness irrespective of the sequence lengths. The previously observed preference to typical sizes is confirmed. Possible reasons for the observed excess of the typical size sequences are discussed.