The digestion of the oxidized B chain of insulin by human neutrophile proteases: elastase and chymotrypsin-like protease.

The specificities of human neutrophile elastase and chymotrypsin-like protease towards oxidized insulin B chain were studied. The neutrophile elastase was found to differ from porcine pancreatic elastase in its specificity towards insulin B chain. The neutrophile elastase preferred mostly valine near the cleaved bond in contrast to pancreatic elastase which preferred alanine as well as valine near the cleaved bond. Human neutrophile chymotrypsin-like protease was found to cleave mostly bonds involving leucine and phenylalanine.