Abstract
We have purified the tissue-type plasminogen activator (t-PA) produced by human melanoma cell line and have investigated its protein-chemical characteristics and fibrinolytic activity. Either one-chain or two-chain t-PA was obtained in the presence or absence of aprotinin during cell culture in purification steps. The N-terminal amino acid sequence of the one-chain t-PA was shown to start with Ser-Tyr-Gln-Val-. The amidolysis of S-2288 by t-PA was found to be greatly altered when the one-chain form was changed to a two-chain form by plasmin or trypsin treatment. When the fibrinolytic activities of t-PA and urokinase (UK) were compared using clot lysis time assay, t-PA and UK having the same unit base were found to have the nearly similar lysis time. On the other hand when fibrin plate assay was used, UK, having a unit of less than 1/10th of that of t-PA, was found to have the same fibrinolytic activity as t-PA.
Furthermore, when the modified Chandler's loop method was used, t-PA was found to be several times more effective than UK in thrombolysis. Whereas UK drastically lowered the amount of fibrinogen and plasminogen in blood, t-PA hardly showed any effect on them.
