Characterization of a plasminogen activator from human melanoma cells cultured in vitro

This thesis describes the work that have been done on the isolation and characterization of a plasminogen activator, Mel-PA, that is released by human melanoma cells cultured in vitro. This enzyme was compared to the urinary plasminogen activator, urokinase. The human melanoma cell line released large amounts of Mel-PA into the surrounding medium when cultured under serum-free conditions. These cells released only one type of plasminogen activator. A technique was developed in which plasminogen activators were seperated electrophoretically and detected in polyacrylamide gel slabs. Mel-PA was concentrated and partially purified by affinity chromatography on benzamidine-sepharose. A study of the distribution of plasminogen activators in tissues and body fluids showed that all mammals examined had two immunochemically distinct plasminogen activators that corresponded, in their distribution, to the urokinase-like and Mel-PA like enzymes of man. A comparitive study of the kinetic behaviour of Mel-PA and urokinase showed numerous differences between the catalytic activities of these two enzymes