Species comparison of renal proteolytic activity for human myelin basic protein peptide 43-88

1. A species comparison was conducted on the proteolytic activity in human, dog, rabbit, guinea-pig and rat kidney which can degrade human myelin basic protein peptide 43-88. 2. In rat kidney the degrading activity occurred over a pH range of 4-11.5 with the greatest activities at pH 5 and 9. The peptide degrading activity in human, dog, rabbit and guinea-pig kidney was considerably less than in the rat and occurred predominantly at pH 7 with lesser activity at pH 9. 3. The effects of inhibitors of proteolytic enzymes indicated that the peptide degrading activities at the same two pH's of dog, rabbit and guinea-pig were similar to one another but differed from that of human. 4. These results indicate that the activity for degrading a potential autoantigenic material is widespread in renal tissue among different species and that different enzymes are involved. More generally, these findings suggest that renal proteinases differ among commonly used laboratory animals and also differ from the human enzymes.