Human blood platelet elastase and proelastase.

Platelet elastase has been differenciated from various protein fractions into a trypsin dependent form and a trypsin independent form. Trypsin independent elastase has been purified by affinity chromatography on cellulose elastin column as a pure protein raction of molecular weight: 26,000 ou SDS acrylamide gels. Trypsin dependent elastase has been purified by preparative acrylamide disc gel electrophoresis. This fraction, proteolysed (limited proteolysis) and activated by trypsin into active elastase, has been identified as the precursor (platelet proelastase) of platelet elastase. Its molecular weight is 28,000 before trypsin and 26,000 after trypsin.