Specific proteolysis of ceruloplasmin by leukocyte elastase.

Ceruloplasmin (Cp) is a major copper transporting plasma protein. The susceptibility of porcine Cp by human leukocyte elastase and plasmin has been investigated. The 116 and 48 kDa bands induced by both proteinases have the same N-terminal sequences which are identical to that of the 132 kDa Cp species, KDKHYYIGIVET. The 70 kDa band generated by elastase has a N-terminal sequence of IGGKVVVYYYIA, and the 68 kDa band generated by plasmin has that of TIIEDAIVGKKV. The 19 kDa bands produced by elastase and plasmin have N-terminal sequences of FNPIKNLLFFLL and VFNPIKNLLFFL, respectively. The novel observations suggest that, in addition to plasmin, leukocyte elastase may play a role in angiogenesis and inflammation by digesting Cp.